CA2007677A1 - Avermectin derivatives - Google Patents
Avermectin derivativesInfo
- Publication number
- CA2007677A1 CA2007677A1 CA 2007677 CA2007677A CA2007677A1 CA 2007677 A1 CA2007677 A1 CA 2007677A1 CA 2007677 CA2007677 CA 2007677 CA 2007677 A CA2007677 A CA 2007677A CA 2007677 A1 CA2007677 A1 CA 2007677A1
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- Prior art keywords
- avermectin
- compounds
- compound
- dehydro
- hydroxy
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Abstract
TITLE OF THE INVENTION
AVERMECTIN DERIVATIVES
ABSTRACT OF THE DISCLOSURE
There are disclosed novel avermectin .DELTA.-23,24-derivatives (also referred to as 23,24-dehydro compounds). The compounds are prepared by selective dehydration of avermectin A2 or B2 compounds. The avermectin compounds have utility as anti-parasitic agents and compositions for that use are also disclosed. The compounds are also highly potent insecticides against agricultural pests. The .DELTA. 23,24-avermectin compounds have increased activity relative to the A2 or B2 compounds.
AVERMECTIN DERIVATIVES
ABSTRACT OF THE DISCLOSURE
There are disclosed novel avermectin .DELTA.-23,24-derivatives (also referred to as 23,24-dehydro compounds). The compounds are prepared by selective dehydration of avermectin A2 or B2 compounds. The avermectin compounds have utility as anti-parasitic agents and compositions for that use are also disclosed. The compounds are also highly potent insecticides against agricultural pests. The .DELTA. 23,24-avermectin compounds have increased activity relative to the A2 or B2 compounds.
Description
5:~7677 TITLE OF THE INVENTION
AVERMECTIN DERIVATIVES
BACKGROUND OF TH _INVENTION
The term avermectin (previously referred to as C-076) is used to dsscribe a series of compounds isolated from the fermentation broth of an avermectin producing strain of StrePtomYces avermitilis and derivatives thereof. The morphological character~
istics of the culture are completely described in U.S. Patent No. 4,~10,519. The avermectin compounds are a series of macrolides, each of which is substi~uted thereon at the 13-position with a 4'-(a-L-oleandrosyl)-a-L-oleandrose yroup. The avermectin compounds and the instant derivatives thereof have a very high degree of anthelmintic and anti-parasitic activity.
Also included in ~he prior art are certain synthetically modified avermectins such as 22,23-dihydro avermectin Bla~81b also known as ivermectin disclosed in U.S. Patent No. 4199569.
~t~
2/DLRll -- 2 -- 17665IA
The avermectin series of compounds, which are isolated from a fermentation broth, have the following structur~:
wherein R is the 4'-(-L-oleandrosyl)-a-L-olean-drose group of the structure:
CH3 2 2 ~f H3 1~ ~ ~19~ ' ~ ~ I
0~5~4 `~ C~13 wherein R is the 4'-(a-L-oleandrosyl)-a-L-olean-drose group of the structure:
~13 C H3 C
~0 ~0 HO~o= II
and wherein the broken line indicates a single or a double bond; Rl is hydroxy and is pres~nt only when said bro~en line indicates a single bond;
R2 is iso-propyl or sec-butyl; and R3 is methoxy or hydroxy.
2/DLRll - 3 - 17665IA
There are eight different major aver~ectin natural product compounds and they are given the designations Ala, Alb, A2a, A2b, Bla, Blb, B2a and B2b based upon the structure of the individual compounds.
In ~he foregoing structural formula, the individual avermectin compounds are as se~ forth below. (The R group is 4'(a-L-oleandrosyl)-a-L-oleandrose~:
Rl R2 R3 Ala (22, 23-Double Bond) sec-butyl -OCH3 Alb (2~,23-Double Bond) lso-propyl -OCH3 A2a -OH sec-butyl -OCH3 A2b -OH lso-propyl - OCH3 Bla (22,23-Double Bond) sec-butyl -OH
Blb (22,23-Double Bond) iso-propyl -OH
B2a -OH sec-butyl -OH
B2b -OH i so-propyl -OH
The avermectin compounds are generally isolated as mixtures of a and b components, Such compounds differ only in the nature of the R2 substituent and the minor structural differences have been found to have very little effect on the isolation procedures, chemical react ivity and biologic~l activity of such ~ompounds.
The 13-deoxy avermectin aglycone compounds, which lack the 13-di~accharide group are also starting materials for the instant compounds. They are disclosed in U.S. Patents Re 32006 and Re 32034.
~20~ 7, 2/DLRll - 4 - 17665IA
The avermectin ~ and 22,23-dihydro avermectin Bl compounds are of superior activity and mixtures of the a and b compounds have been selected to be marketed for their broad spectrum antiparasitic activity against both animal and plant parasites.
The avermectin A2 and B2 compounds are of a considerably lower level of activi~y and are not marketed products. However, the conversion of thQ A2 and B2 compounds to ~he 23-deoxy-~23,24-avermectin compounds produces compounds of significantly higher levels of activity. Thus, the A2 and B2 compounds, which would normally be discarded in the preparation of the Bl and 22,23-dihydro Bl compounds, are utili~ed in the preparation of compounds with levels of activity commensurate with marketed products.
SUMMARY OF THE INVENTION
The ins~ant invention is concerned with certain deriva~ives of avermectin compounds wherein the 23-hydroxy group of avermectin A2 and B2 compounds is selec~ively eliminated to form 23-deoxy-23,24 bis-dehydro compounds of significan~ levels of anti-par~sitic activity. Thus it is an object of the instant invention to describe such avermectin elimination products. A further object is to describe proce~ses for the prepara~ion of such compounds. A still urther object is to d~scribe the uses of such compou~ds as anti-parasitic and insecticidal agents. Still further objects will become apparent from a reading of ~he following description.
AVERMECTIN DERIVATIVES
BACKGROUND OF TH _INVENTION
The term avermectin (previously referred to as C-076) is used to dsscribe a series of compounds isolated from the fermentation broth of an avermectin producing strain of StrePtomYces avermitilis and derivatives thereof. The morphological character~
istics of the culture are completely described in U.S. Patent No. 4,~10,519. The avermectin compounds are a series of macrolides, each of which is substi~uted thereon at the 13-position with a 4'-(a-L-oleandrosyl)-a-L-oleandrose yroup. The avermectin compounds and the instant derivatives thereof have a very high degree of anthelmintic and anti-parasitic activity.
Also included in ~he prior art are certain synthetically modified avermectins such as 22,23-dihydro avermectin Bla~81b also known as ivermectin disclosed in U.S. Patent No. 4199569.
~t~
2/DLRll -- 2 -- 17665IA
The avermectin series of compounds, which are isolated from a fermentation broth, have the following structur~:
wherein R is the 4'-(-L-oleandrosyl)-a-L-olean-drose group of the structure:
CH3 2 2 ~f H3 1~ ~ ~19~ ' ~ ~ I
0~5~4 `~ C~13 wherein R is the 4'-(a-L-oleandrosyl)-a-L-olean-drose group of the structure:
~13 C H3 C
~0 ~0 HO~o= II
and wherein the broken line indicates a single or a double bond; Rl is hydroxy and is pres~nt only when said bro~en line indicates a single bond;
R2 is iso-propyl or sec-butyl; and R3 is methoxy or hydroxy.
2/DLRll - 3 - 17665IA
There are eight different major aver~ectin natural product compounds and they are given the designations Ala, Alb, A2a, A2b, Bla, Blb, B2a and B2b based upon the structure of the individual compounds.
In ~he foregoing structural formula, the individual avermectin compounds are as se~ forth below. (The R group is 4'(a-L-oleandrosyl)-a-L-oleandrose~:
Rl R2 R3 Ala (22, 23-Double Bond) sec-butyl -OCH3 Alb (2~,23-Double Bond) lso-propyl -OCH3 A2a -OH sec-butyl -OCH3 A2b -OH lso-propyl - OCH3 Bla (22,23-Double Bond) sec-butyl -OH
Blb (22,23-Double Bond) iso-propyl -OH
B2a -OH sec-butyl -OH
B2b -OH i so-propyl -OH
The avermectin compounds are generally isolated as mixtures of a and b components, Such compounds differ only in the nature of the R2 substituent and the minor structural differences have been found to have very little effect on the isolation procedures, chemical react ivity and biologic~l activity of such ~ompounds.
The 13-deoxy avermectin aglycone compounds, which lack the 13-di~accharide group are also starting materials for the instant compounds. They are disclosed in U.S. Patents Re 32006 and Re 32034.
~20~ 7, 2/DLRll - 4 - 17665IA
The avermectin ~ and 22,23-dihydro avermectin Bl compounds are of superior activity and mixtures of the a and b compounds have been selected to be marketed for their broad spectrum antiparasitic activity against both animal and plant parasites.
The avermectin A2 and B2 compounds are of a considerably lower level of activi~y and are not marketed products. However, the conversion of thQ A2 and B2 compounds to ~he 23-deoxy-~23,24-avermectin compounds produces compounds of significantly higher levels of activity. Thus, the A2 and B2 compounds, which would normally be discarded in the preparation of the Bl and 22,23-dihydro Bl compounds, are utili~ed in the preparation of compounds with levels of activity commensurate with marketed products.
SUMMARY OF THE INVENTION
The ins~ant invention is concerned with certain deriva~ives of avermectin compounds wherein the 23-hydroxy group of avermectin A2 and B2 compounds is selec~ively eliminated to form 23-deoxy-23,24 bis-dehydro compounds of significan~ levels of anti-par~sitic activity. Thus it is an object of the instant invention to describe such avermectin elimination products. A further object is to describe proce~ses for the prepara~ion of such compounds. A still urther object is to d~scribe the uses of such compou~ds as anti-parasitic and insecticidal agents. Still further objects will become apparent from a reading of ~he following description.
3~ 7 2/DLRll - 5 - 17665IP.
DESCRIPTION OF THE INVENTION
The compounds of the instant invention have the following structural formula.
C}13 H 22~f ~3 H C' ~ l'H
f 0~5 H 3~ 3 wherein A represents a single bond or a double bond, Rl is iso-propyl or sec-butyl;
R2 is hydroxy, ketone, loweralkoxy, or protected ~ hydroxy;
R3 is hydrogen, halogen, or ketone, however R3 is present only when A represents a single bond;
R4 's hydrogen, hydroxy, halogen, ~0~77 2/DLRll - 6 - 17665IA
R~ ~-- or R~
H,CC~ H3CC~ H,CO
R5 is hydroxy, ketone, -NR6R7 or =NHNC-NR6R7; and R6 and ~7 are independently hydrogen, loweralkyl or loweralkanoyl.
In the instant description, the term "loweralkyl" is intended to include those alkyl groups containing from 1 ~o 6 carbon atom~ in either a straight or branched chain or a cyclic configuration of from 3 to 6 carbon atoms. Exemplary of such alkyl groups are methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, pentyl, hexyl, cyclopentyl, cyclohexyl and the like.
The term "loweralkanoyl" is intended to include those alkanoyl groups of from 2 to ~ carbon atoms of either a straight or branched chain. Such groups are exempli~ied by acetyl, propionyl, butyryl, pentanoyl, hexanoyl and the 1 lkP, The term "halogen" is intended to include the halogen atom, fluorine, chlorine, bromine and iodine.
Preferred compounds of this invention are realized in the above structure wherein:
7~;7t;, 2/DLRll - 7 - l766sIA
A i~ a single, or a double bond; Rl is isopropyl, or sec-butyl; R2 is hydroxy; R3 is hydrogen, halogen, hydroxy or oxo: R4 is hydrogen, hydroxy, halogen, 4'-R5 ~a-L-oleandrosyloxy), 4"-Rs-~4'-(a-L-oleandrosyl)-a-L-oleandrosyloxy]; and R5 is hydroxy, amino, loweralkylamino, diloweralkylamino.
Additional preferred compounds are realized when R4 is halogen, and in particular, when R4 is fluorine, and Rl, R2, R3 and R5 are as defined above.
lo Examples of preferred compounds of this invention are realized in the following:
23,24-dehydro avermectin B2a/B2b " " A2a/A2b ~ B2a/B2b aglycone " " B2a/B2b monosaccharide " -13-deoxy avermectin B2a/B2b aglycone " -10,11-dihydro " B2a/B2b " " " B2a/B2b monosaccharide " " B2a/B2b aglycone " -13-deoxy-10,11-dihydro avermectin B2a/B2b aglycone " -10,11-dihydro-10-fluoro " B2a/B2b " " " " B2a/B2b monosaccharide ~ ~' " " B2a/B2b aglycone ~ -13-deoxy-10,11--dihydro-10-fluoro avermectin B2a/B2b aglycone " 4"-deoxy-4"-methylamino avermect;n B2a~B2b " " 4"-amino " B2a/B2b 4"-dimethylamino " B2a/B2b 4"-oxo avermectin B2a/B2b semicarbazone " l~ ~ B2a/B2b(4-methylsemicarbazone) " " " B2a/B2b~4,4-dimethylsemicarbazone) 23,24-dehydro-13-deoxy-13-fluoroavermectin B2a/B2b aglycone ~:q~ 7~
2/DLRll - 8 - 17665IA
The "b" compounds, those with a 25-iso-propyl group, are somewhat di~ficult to ~eparate from the corresponding "a" compound with a 25-sec-butyl group and as such the compounds are generally isolated as mixtures of the two compounds. Thus references in the instant application to "a"
compounds such as Bla, Ala, and the like, are construed to define the pure compound as well as those which actually contain a certain proportion of the corresponding "b" compound.
Alternatively, this representation of a mixture is sometimes done by referring, for example, to "the Bl or B2 compounds" or by separating the "a"
compound from the "b" compound by a slash (/) such as Bla/Blb, B~a/B2b and the like.
The compounds of the instant invention differ from other avermectin compounds in that the 23-hydr~xy compounds, A2 and B2 compounds are converted into 23-dehydroxy-Q23,24 compounds, Such compounds are significantly superior to the A2 and B2 starting materials in their antiparasitic activity.
The instant compounds are prepared from the suitably protec~ed avermectin A2 or B2 compound, that is a compound with an unprotected 23-hydroxy group but with all other hydroxy groups protected. This compound is treated with the reagent diethylamino sulfurtrifluoride, generally referred to as DAST.
2~30~ 7 2/DLRll - 9 - 17665IA
This reagent is generally known in the art as a fluorinating reagent, however when used under the below described conditions and on the instant compounds, there is observed the surprising result S that no fluoridation occurs anywhere on the avermectin molecule. The unprotected 23-hydroxy group is removed and a 23-24 double bond (a 23,24) is formed.
The reaction is represented in the following reaction scheme.
OH
CH3 22/~ 3 ,~17 ~o~
CH3 ~1 1 1 8 \1~, ~2 0 H
H A o o )7~7~7 2/DLRll -- 10 -- 17665IA
~DAST ~23 H3 CH3 22 `~
R- ~ D~ R~
R3 ~ (I~
~?2 The reaction is carried out initially at a reduced temperature due to the r~activity of D~ST.
Generally temperatures of from -50C to -100C are utilized. It is preferred to carry out ~he reaction at about -78C since this is the temperature which is achieved by placing the reaction vessel in a dry-ice (solid carbon dioxide-acetone) bath. To ~urther avoid side-reactions, the reaction is preerably carried out under a blanket of nitrogen an other inert atmosphere. The reaction is maintained at the reduced temperatures from 10 to 1~0 minutes and then is generally rai~ed to room temperature slowly, over a : period of from 60 to 180 minutes. To complete the 37~77 2/DLRll - ll - 17665IA
reaction, the reaction vessel may be maintained at room temperature for from 1 to 8 hours or until analysis of aliquots of the reaction mixture indicate that the reaction is complete. Generally analy~ical procedures which can follow the disappearance of the 23-hydroxy group will give a good indication of the degree to which the reaction has progressed to completion. The product is isola~ed using standard techniques known to those sXilled in the art and the protecting groups are removed following the procedures described below.
P~EPARATION OF STARTING MATERIALS
The ultimate starting materials for the compounds of this invention are the avermectin fermentation products defined above which have the isopropyl or sec-butyl group at the 25-position.
T~us it is apparent that additional reactions are required to prepare many of the immediate starting materials for the instant compounds. Specifically, reactions are carried out at the ~', 4", 5', 10, ll and 13, positions. In addition, during the various reactions described above, and below it may be necessary ~o protect various reactive groups to prevent the undesired reaction of such groups. In addition, protection of such reactive groups may facilitate ~he separation of the various products.
With the appropriate positions protected, the DAST
reaction may be carried out without affecting the remainder of the molecule. Following the described reactions, the pro~ecting groups may be removed and the unprotected product isolated. The protecting 2(~ 7~77 2/DLRll - 12 - 17S65IA
group employed is ideally one which may be readily synthesized, will not be affected by the reaction with the various reagents employed and may be readily removed without affecting any other functions of the molecule. It is noted that the instant protected compounds are novel and have considerable antiparasitic activity. They are included within the ambit of the instant invention. One preferred type of protecting group for the avermectin type of molecule is the tri-substituted silyl group, preferably the trialkyl silyl group. One especially preferred example, is the t-butyl dimethylsilyl group. The reaction preparing the protected compound i5 carried out by reactiny a hydroxy compound with the appropriately substituted silylhalide, preferably the silylchloride in an aprotic polar solvent such as dimethylformamide. Imidazole is added as a catalyst. The reaction is complete in from 1 to 24 hours at from 0 to 25C. For the 5-position hydroxy group the reaction is complete in from 1/2 to 3 hours at from 0C to room temperature. This reaction is selective to the 5 position under the conditions above described and very little, if any, silylation is observed at other hydroxy substituted positions.
The silyl groups are then removed after the other reactions have been carried out. The silyl group or groups are remo~ed by stirring the silyl compound in methanol catalyzed by a catalytic ~mount of an acid, preferably a sulfonic acid such as p-toluene sulfonic acid. The reaction is complete in about 1 to 12 hours at from 0 to 50C. Alternatively, the silyl group or groups can be removed with a hydro-2~")~t~
2/DLRll - 13 - 17665IA
gen fluoride-pyridine complex in an organic solvent such as tetrahydrofuran. The reaction is complete in from about 3 ~o 24 hours and is preferably carried out at room temperature.
Additional reactions which may be carried out to prepare the compounds of ~his invention are the selective removal of one of the a-L-oleandrosyl moieties (described in U.S. Paten~ 4,206,205 to Mrozik et al.).
lo The reaction conditions which are generally applicable to the preparation of both the mono-saccharide and aglycone involve dissolving ~he avermectin compound or the hydrogenated avermectin compound in an aqueous acidic non-nucleophilic lS organic solvent, miscible with water, preferably dioxane, tetrahydrofuran, dimethoxyethane, dimethyl formamide, bis-2-methoxye~hyl ether, and the like, in which the water concentration is from 0.1 to 20~ by volume. Concentrat~d sulfuric acid is added to the aqueous organic solvent to the extent of 0.01 to 10%
by volume. Th~ reaction mixture is generally stirred at about 20-40C, preferably at room temperature, or from 6 to 24 hours. The lower conc ntration of acid, from about 0.01 to 0.1% will predominately produce the monosaccharide under ~he above reaction conditions. Higher acid concentrations, from about 1 to 10% will predominantly produc~ the aglycone under the above reaction conditions. Intermediate acid concentratiQns will generally produce mixtures of monosaccharide and aglycone. The products are isolated, and mixtures are separated by ~echnigues 2(~7~7~
2/DLRll - 14 - 17665IA
such as column, thin layer preparative and high pressure li~uid chromatography, and other known techniques.
The acids which may be employed in the above process include mineral acids and organic acids such as sulfuric, hydrohalic, phosphoric, trifluoroacetic, trifluoro methane sulfonic and the like. The hydro-halic acids are preferably hydrochloric or hydro-bromic. The preferred acid in the above process is sulfuric acid.
A further procedure for the preparation of the monosaccharide or aglycone of the avermectin compounds or of the hydrogenated avermectin compounds utilizes a different solvent system for ~he mono-saccharide and the aglycone. ThP procedure for the preparation of the monosaccharide uses 1% acid by volume in isopropanol at from 20-40C, preferably room temperature, for from 6 ~o 24 hours. For ~he preparation of the aglycone, 1% acid, by volume, in methanol under the foregoing reac~ion condi~ions has been found to be appropriate.
Any strong inorganic or organic acid is appropria~e for this process, and again sulfuric acid is the preferred acid.
It has also been observed that the mono-saccharide is prepared during the course of the reackion used to remove the trialkylsilyl protecting group. Since acid catalysis is used to remove the pro~ecting group, ~his is expected. However, in such cases, both the desired product and the monQsaccharide are prepared and they can be readily separated using the above-described ~echniques.
7~7 2/DLRll - 15 - 17665IA
In thP preparation of the 4' or 4" keto or amino substituted compounds, the avermectin startin~
materials are oxidized at the 4' or 4"-position to the corresponding keto compound. The procedures for the preparation of such compounds are described in U.S. Patent 4427663 to Mrozik. During the procedure the presence of any hydroxy groups at the 5 and 23-position will require tha~ such hydroxy groups be protecte~ in order that they too are not oxidized.
The 7-hydroxy group is very unreactive and need not be protected. The procedure used to prepare the protected intermediates are described above. The oxidation reaction is carried ou~ in an inert solvent such as methylene chloride using oxalyl chloride or trifluoroacetic anhydride with dimethylsulfoxide as the oxidizing agent. The reaction proceeds by dissolving the oxalyl chloride or trifluoroacetic anhydride and dimethylsulfoxide (or other oxidizing reagents3 in methylene chloride cooled to fro~ -50 to -80C and adding dropwise a methylene chloride solution of the avermectin compound to be oxidized, The addition is carried out over a period of ~rom 15 minutes to 1 hour and then trie~hylamine is added dropwise over a period of from 1 to 15 minutes. The reaction mixture is then allowed to warm to room temperature over a period of from 1/2 to 1 hour. The 4' or 4"-keto compound is isolated using techniques known to those skilled in the art.
In the next step, the 4' or 4"-keto compound is aminated to prepare the unsubstituted amino compound (R6=R7=hydrogen). The reaction is carried OU't in an inert solvent such as methanol at from -10 37~7~
2/DLRll - 16 - 17665IA
to +25OC usiny ammonium salts and sodium cyanoboro-hydride as the aminating and reducing reagents, respectively. The reaction is complete in from 15 minutes to 24 hours and the product 4"-deoxy 4"-amino compound is isolated using techniques known to those skilled in the art. Sui~able ammonium salts are the acetate, propionate, benzoate and the like. The acetate is preferred.
As a variation to the foregoing amination reac~ion, m~hyl ammonium salts can be used in place of the ammonium salts to prepare the monomethyl substituted compound directly. The same reagents, salts and reaction conditions as described above can be used for such a reaction.
The substitution reaction wherein the substituent is an acyl function is carried out using an acylating reagent in the presence of a base in an inert solvent~ The acylation of avermec~in compounds, is fully described in U.S. Patent 4201861 to Mrozik et al~ The preferred acylating reagents are loweralkanoyl anhydrides, loweralkanoyl halides, substituted benzene sulfonyl chlorides, lower alkyl sulfonyl chlorides, and the like~ The reaction is carried out in an inert solvent such as methylene chloride in the presence of a non-reactive base such as pyridine or triethylamine in ~rder to neutralize the acid produced during the course of the rea~tion.
The reaction temperature is from -10 ~o ~5C and the reaction is complete in from 5 minutes to 8 hours.
The product is isolated using known technigues~
The reaction for the preparation of the 4'-or 4"-deo~y-4'- or ~"-dialkylamino compounds is ~0~6~)~
2/DLRll - 17 - 176~5IA
carried out using the alkylating reaction conditions of an exce6s of a carbonyl compound, preferably formaldehyde and a reducing agent such as sodium cyano borohydride, in methanol. The reaction is carried out in a solvent suitable to dissolve the organic starting material using excess aqueous formaldehyde along with the presence of a small amount of acid such as acetic acid to facilitate the reaction. The reaction is carried out at from 10 to ~25C with the solution of the avermectin compound in methanol added dropwise over a period of from 30 to 60 minutes to the alkylating reagent mixture and the product is isolated using known techniques.
Further reactions of the avermectin compounds either before or after the DAST reaction are possible to prepare the compounds of this invention.
~ Following the preparation of the aglycone (R4 is hydroxy at the 13 position), U.S. Patents Re 32006 and Re 32034 to Chabala et al. disclose the hydroxy group displacement with a halogen using a reagent such as benzene sulfonylhalide, and the halogen is removed by reduction using a reducing agent such as trialkyltin hydride.
The hydroxy group at 5 may be alkylated following the procedures described in U.S. Patent 4200581 to Fisher et al.
The novel compounds of ~his inv~ntion have significant parasiticidal activity as anthelmintics, ectoparasiticides, insecticide~ and acaricides, in human and animal health and in agriculture.
The disease or group of diseases described generally as helminthiasis is due to infection of an 2~07fi7~
2/DLRll - 18 - 17665IA
animal host with parasitic worms known as helminths.
Helminthiasis is a prevalent and serious economic problem in domesticated animals such as swine, sheep, horses, cattle, goats, dogs, cats and poultry. Among the helminths, the group of worms described as nematodes causes widespread and often times serious infection in various species of animals. The most common genera of nematodes infecting the animals referred ~o above are Haemon~hus, TrichostronqYlus, Ostertaqia, Nematodirus, Cooperia, Ascaris, Bunostomum, OesoPhaqostomum~ Chabertia, Trichuris, Stronqylus, Trichonema, DictYocaulus, CaPillaria, Heterakls, Toxocara, Ascaridia, OxYuris, AncYlostoma, Uncinaria, Toxascaris and Parascaris. Certain of these, such as Nematodirus, Cooperia and Oesophaqostomum attack primarily the intestinal tract while others, such as Haemonchus and Os~ertaqia, are more prevalent in the stomach while still others such as Dictyocaulus are found in the lungs. Still other parasites may be located in other tissues and organs of the body such as the heart and blood vessels, subcutaneous and lymphatic tissue and the like. The parasitic infections known as helminthiases lead to anemia, malnutrition, weakness, weight loss, severe damage to the walls of the intestinal tract and other tissues and organs and, if left untreat~d, may result in death of the infected host. The substituted avermectin compounds of this invention have unexpectedly high activity against the~e parasites, 3~ and in addition are also active against Dirofilaria in dogs, Namatospiroides, SyPhacia, AsPiculuris in rodents, arthropod ectopara ites of animals and birds Z(~f.`~
2/DLRll - 19 - 17665IA
such as ticks, mites, lice, fleas, blowfly, in sheep Lucilia sp., biting insects and such migrating diperous larvae as HYpoderma sp. cattle, GastroPhilus in hor~es, and Cuterebra sp. in rodents.
The instant compounds are also useful against parasites which infect humans. The most common genera of paxasites of the gastro-intestinal tract of man are AncYlostoma, Necator, Ascaris, StronqYloides, Trichinella, Ca~illaria, Trichuris, and Enterobius.
Other medically important genera of parasites which are found in the blood or other tissues and or~ans outside the gastrointestinal tract are the filiarial worms such as Wuchereria, Bruqia, Onchocerca and Loa, Dracunculus and extra intestinal stages of the intestinal worms Stronqyloides and Trichinella. The compounds are also of value against arthropods parasitizing man, biting insects and other dipterous pests causing annoyance to man.
The compounds are also active against house-hold pests such as the cockroach, Blatella sP., clothes moth, Tineola sp., carpet beetle, Attaqenus sP., and the housefly Musca domestica.
The compounds are also useful against insect pes~s of stored grains such as Tribolium sP., Tenebrio sp. and of agricultural plants such as two-spotted spider mites, (Tetranychus sP.), aphids, ~AcYrthiosiphon sp.); against migratory orthopterans such as locusts and immature stages of insects living on plant tissue. The compounds are useful as a nematocide for the control of soil nematodes and plant parasites such as Meloidoqyne ~E~ which may be of importance in agriculture The compounds are ~0~:~'7677 2~DLRll - 20 - 17665IA
active against other plant pests such as the southern army worm and Mexican bean beetle larvae.
These compounds may be administered orally in a unit dosage form such as a capsule, bolus or 5 tablet, or as a liquid drench where used as an anthelmintic in mammals. The drench is normally a solution, suspension or dispersion of the active ingredient usually in water ~ogether with a sus-pending agent such as bentonite and a wetting agent or like excipient. Generally, the drenches also contain an antifoaming agent. Drench formulations generally contains from about 0.001 to 0.5% by weight of the active compound, Preferred drench formula-tions may contain from 0.01 to 0.1% by weight. The capsules and bo}uses comprise the active ingredient admixed with a carrier.vehicle such as starch, talc, magnesium stearate, or di-calcium phosphate.
- Where it is desired to administer the avermectin derivatives in a dry, solid unit dosage form, capsules, boluses or tablets containing the dçsirPd amount of active compound usually are em-ployed. These dosage forms are prepared by inti-ma~ely and uniformly mixing ~he active ingredient with suitable finely divided diluents, fillers, disinte~rating agents and/or binders such as starch, lactose, talc, magnesium steara~e, vegetable gums and the like. ~uch uni~ dosage formulationæ may be varied widely with respec~ to their total weight and content of ~he antiparasitic agent depending upon factors such as the ~ype of host animal to be treated, the severity and type of infection and the weight of the host.
)7~'7 2/DLRll - 21 - 17665IA
When the active compound is to be adminis-tered via an animal feedstuff, it is intimately dispersed in the feed or used as a top dressing or in the form of pellets which may then be added to the finished feed or optionally fed separately. Alterna-tiv~ly, the antiparasi~ic compounds of our invention may be administered to animals parPntPrally, ~or example, by intraruminal, intramuscular, intra-tracheal, or subcutaneous injection in which event the active ingredient is dissolved or dispersed in a li~uid carrier vehicle. For parenteral adminis-tration, the active material is suitably admixed with an acceptable vehicle, preferably of the vegetable oil variety such as peanut oil, cotton seed oil and the like. Other parenteral vehicles such as organic preparation using solketal, glycerol formal, and aqueous parenteral formulations are also used. The active avermectin compound or compounds are dissolved or suspPnded in the parenteral formulation for administration; such formulations generally contain from 0.005 to 5% by weight of the active compound.
Although ~he antiparasitic agents of this in~ention find their primary use in the tr~atment and/or prevention of helminthiasis, they arP also useful in the prevention and treatment of diseases caused by other parasites, for example, arthropod parasites such as ticks, lire, fleas, mites and other biting insects in domesticated animals and poultry.
They are also effective in treatment of parasitic diæeases that occur in other animals including humans. The optimum amount to be employed for best results will, of course, depend upon the particular '76~7 2/DLRll - 22 - 17665IA
compound employed, the species of animal to be treated and the type and severi~ of parasitic infection or inf estation. Generally good results are ob~ained with our novel compounds by the oral administration of from about 0.001 to 10 mg per kg of animal body weight, such total dose being given at one time or in divided doses over a relatively short period of time such as 1-5 days. With the preferred compounds of the invention, excellent control o~ such parasites is obtained in animals by administering from about 0.025 to 0.5 mg per kg of body weight in a single dose. Repeat tr~atments are given as required to combat re-infections and are dependent upon the species of parasite and the husbandry techniques being employed. The techniques for administering these materials to animals are known to those skilled in the veterinary field.
~ hen the compounds des~ribed herein are administered as a component of the feed of the animals, or dissolved or suspended in the drinking water, compositions are provided in which the active compound or compounds are intimately dispersed in an inert carrier or diluent. By inert carrier is meant one that will not react with the antiparasitic agent and one that may be administered safely to animals.
Preferably, a carrier for feed administration is one that is, or may be, an ingredient of the animal ration.
~uitable composi~ions include feed premixes or supplements in which the active ingredient is present in relatively large amounts and which are suitable for direct feeding to ~he animal or for 2~ 7~;77 2/DLRll - 23 - 17665IA
addition to the feed either directly or after an intermediate dilution or blending step. Typical carriers or diluents suitable for such compositions include, for example, distillers' dried grains, corn meal, citrus meal, fermentation residues, ground oyster shells, wheat shorts, molasses solubles, corn cob meal~ edible bean mill feed, soya grits, crushed limestone and the like. The active compounds are intimately dispersed throughout the carrier by methods such as grinding, stirring, milling or tumbling. Compositions containing from about 0.005 to 2.0~ by weight of the active compound are particu-larly suitable as feed premixes. ~eed supplements, which are fed directly to the animal, contain from about 0.0002 to 0.3~ by weight of the active com~
pounds.
Such supplements are added to the animal feed in an amount to give the finished feed the concentration of active compound desired for ~he treatment and control of parasitic diseases.
Although ~he desired concPntration of active compound will vary depending upon the factors previously mentioned as well as upon ~he particular avermectin derivative employed, the compounds o~ this invention are usually fed at concentrations of be~ween 0.00001 to 0.002% in the feed in order to achieve the desired antiparasi~ic result.
The avermectin compounds of this invention are also useful in combatting agricultural pests that inflict damage upon crops while they are growing or while in storage. The compounds are applied using known teohnigues as sprays, dus~s, emulsions and thP
~:~3~
2/DLRll - 24 - 17665~A
like, to the growing or stored crops to effect protection from such agricultural pests.
In using the compounds of this invention, the individual substitutPd avermectin components may be prepared and used in that form. Alternatively, mixtures of two or more of the individual avermectin components may be used, as well as mixtures o the parent avermectin compounds, other avermectin compounds or o~her ac~ive compounds not related to avermectin, wi~h the compounds of this invention.
In the isolation of the avermectin compounds, which serve as starting materials for the instant processes, from the fermentation broth, the various avermectin compounds will be found to have lS been prepared in unequal amounts. In particular an "a" series compound will be prepared in a higher proportion than the corresponding "b" series compound.
The difference between the "a" series and "b" series is constant throughout t~e avermectin compounds and consists of a sec-bu~yl group and an iso-propyl group respectively at the 25 position. This difference, of course, does not interfere with any of the ins~ant reactions. In particular it may not be necessary to separate the "~" components from the related "a"
component. Separation of these closely rela~ed compounds is generally not practiced æince the "b"
compound is present only in a small percent by w~ight, and the structural difference has negligible effect on the reaction processes and biological activities.
In par~icular it has been found that the starting materials for ~hP compounds of this inven-tion are very often prepared in a ratio of about 80 Z(-~C)7'67'~
2/DLRll - 25 - 17665IA
avermectin Bla or Ala and 20% avermectin Blb or Alb.
Thus the preferred composition of this invention is one which contains about 80% of the "a" component ~nd 20% of ~he "b" componen~.
The following examples are provided in order that this invention might be more fully understood;
they are not to be construed as limitative of the invention.
The substitu~ed avermectin derivatives lo prepared in the following examples are generally isolated as amorphous solids and not as crystalline solids. They are thus characterized analytically using techniques such as mass spectrometry, nuclear magnetic resonance, and the like. Being amorphous, the compounds are not characterized by sharp melting points, however, the chroma~ographic and analytical methods employed demonstrate the puri~y of the compounds.
In the following examples, the various starting materials therefor are avermectin compounds or derivatives of avermectin c~mpounds. The avPr-mectin compounds and the preparation and isola~ion thereof from fermentation broths are described in United S~ates Patent No. 4,310,519 issued 12 January 1982. The 22,23-dihydro derivatives of avermectin compounds are described in U.S. Patent 4,199,5~9.
The aglycone and monosaccharide derivatives o~
avermectin compounds are described in U. æ . Patent 4,~06,205. The 13-deoxy ~ompounds are described in U.S. Patents R~ 32006 and Re 32034.
~3~ 677 Z/DLRll - 26 - 17665IA
The 4' and 4" amino compounds are described in U.S.
Patent 4,427,6~3. The acyl derivatives are disclosed in U.S. Patent 4201861. The epoxide derivatives are disclosed in U.S. Patent 4,530,971. The 13-keto and amino compounds are disclosed in U.S. Patent 4,579,864, and the o-alkyl compounds are disclosed in U.S. Patent 4,200,581. The 13-(alkoxy)methoxy compounds are disclosed in U.S. Patent 4,587,247.
The following examples are being provided in order that the invention may be more fully understood.
They are not to be construed as being limitative of the invention.
4",5-Di-O-tert-butyldimethylsilyl-avermectin B2a and/or B2b _ _ _ A solution of 1.0 g of avermectin B2a and/or B2b, 0.614 g of imidazole, 0.680 mg of tert-butyl-dimethylsilyl chloride in 12.3 ml of anhydrous DMF
was stirred at room temperature under N2 for 20.5 hours. Then water and ether were added, the organic phase separated, washed repeatedly with water and concentrated in vacuo. Puxification by silica gel column chromatography gave 401 mg of 4",5,23-tri-O-~ert-butyldimethylsilyl-avermectin B2a and/or B2b, ~37 mg of the desired 4",5-di-O-tert-butyldimethyl-6ilyl-avermectin B2a and/or B2b, 11~ mg of 5,23-di-O-t:ert-butyldimethylsilyl-~vermectin B2a and~or B2b, and 129 mg of 5-O-tert-butyldimethylsilyl-avermectin B2a and/or B2b, all of which were charac~erized by their mass and/or ~H-NMR spectra.
2/DLRll - 27 - 17665IA
4",5-Di-O-tert-butyldimethylsilyl-7,23-di-O-trimethylsilYl avermectin B2a and/or B~b To a solution containing 100 mg of 4",5-di-O-tert-butyldimethylsilyl-avermectin B2a and/or B2b in 0.5 ml of anhydrous DMF 1.O ml ~f bis~trimethylsilyl)trifluoroacetamide was added dropwise. The reaction mixture was held 3 hours at room temperature and then evaporated in vacuo and high vacuum to a glass. This was shown to be more than 90 % pure and assigned the structure of 4",5-di-O-tert-butyldimethylsilyl-7,23-di-O-tri-methylsilyl avermectin B2a and/or B2b in analogy to similar reactions. The crude product was used immediately for ~he next step.
4",5-Di-O-tert-butyldimethylsilyl-7-O-trimethylsilyl avermectin B2a and/or B2b _ A solution of 480 mg of 4",5-di-O-tert-butyldimethylsilyl-7~23-di-O-trimethylsilyl avermectin B2a and/or B2b in 100 ml of THF, 15 ml of water, and ~.4 ml of glacial acetic acid was held at room ~emperature for 20 hours. Th~n the reaction mixture was concentrated to a ~maller volume in high vacuum at room temperature. Water and EtOAc were added, and the solution was made slightly ba~ic with NaHC~3. The organic phase was separated and worked up to give 460 mg of a light yellow foam, which was characterized by its mass and lH-NMR spectra as 4",5-di-O-tert-butyldimethylsilyl-7-O tri-methylsilyl avermectin B2a and/or B2b.
æ~ 67 ~
4",5-Di-O-tert-butyldimethylsilyl-7-O-trimethylsilyl-23,24-dehYdroa~ermectin B2a and/or B2b To a solution of 13.3 microL of diethyl-aminosulur trifluoride (DAST) in 0.5 ml of anhydrousCH2C12 stirred at minus 78C under N2 was added a solution of 100 mg of 4",5-di-O-tert-butyldimethyl-silyl-7-O-trimethylsilyl avermectin B2a and/or B2b in 0.5 ml of anhydrous CH2C12. The reaction mixture was held 30 minutes at minus 78~C, followed by 60 minutes at minus 20C and 90 minutes at room temperature. The reaction product was isolated by addition of dilute NaHCO3 solution and extraction with ether giving 87 mg of light colored foam. TLC analysis showed at least three reaction products. Purification by preparative silicagel layer chromatography ga~e 33 mg of a pure sample as white foam which was assigned the structure of 4",5-di-O-tert-butyldimethylsilyl-7-O~
trimethylsilyl-23,24-dehydroavermectin B2a and/or B2b by its mass and lH-NMR spectra. The structure was confirmed by further spectral investigation of the deprotected compound.(See Example 5).
23,24-DehYdroavermectin ~2a and/or B2b A solution of 33 mg of 4",5-di-O-tert-butyldimethylsilyl-7-O-trimethylsilyl-23,24-dehydro-avermectin B2a and/or B2b in 2.0 ml of an anhydrous hydrogen fluoride - pyridine - tetrahydrouran ~o mixture, prepared by mixing 14.0 ml of THF, 4.0 ml of pyridine and 2.0 ml of commercial HF - pyridine (consisting of 70 % HF and 30 ~ of pyridine, supplied by Aldrich Chemical Company) was kept at room ~ ~ O 7 ~ ~7 2/DLRll - 29 - 17665IA
temperature for two days. Then the reaction mixture was poured into dilute aqueous sodium bicarbonate ~olution and extracted with EtOAc to give 27 mg of 23,24-dehydroavermectin B2a and/or B2b as a glass, which was fully characterized by its W ~pectrum, EI
and FAB ma~s spec~ra, and lH-, and 13C-NMR spectra includin~ lH-"COSY" and 13C-APT.
23,24-Dehydroavermectin A2a and/or A2b When avermectin A2a and/or A2b is reacted in accordance to the procedures described in examples 1, 2, 3, 4, and 5, 23,24-dehydroavermectin A2a and/or A2b is obtained, which can be characterized by its mass spectrum and lH-, and 13C-NMR spectra.
~3,24-Dehydro-13-deoxyavermectin B2a and/or B2b aqlYcone When 13-deoxyavermectin B2a and/or B2b aglycone is reac~ed in accordance to the procedures described in examples 1, 2, 3, 4, and 5, then 23,24-dehydro-13-deoxyavermectin B2a and/or B~b aglycone is obtained, which can be characterized by its mass spectrum and lH-, and 13C-NMR spectra.
Exam~le 8 5-O-t-Butyldimethylsilyl-23, 24-dehydroavermect in B2a and/or B2b . . .
A solution of 130 mg of 23,2~-dehydro-avermectin B2a, 68 mg of imidazole, and ~1 mg of tert-butyldimethylsilyl chloride in 1.5 ml of DMF is ~n(~7~
2/DLRll - 30 - 17665IA
stirred at room temperature for 45 min. The reaction mixture is then poured into water. The product is extracted with ether; the extrac~ is washed with water, dried and concentrated in vacuo to a light foam. Purification by preparative ~ilica gel thin layer chromatography with CH2C12-EtOAc 85:15 solvent mixture gives 5-O-t-bu~yldimethylsilyl 23,24-dehydroavermectin B2a and/or B2b, which is characterized by NMR and mass spec~ra.
ExamPle 9 5-O-t-Butyldimethylsilyl-23,24-dehydro-4"-oxoaver-mectin B2a and/or B2b A solution of 57 mg (0.04 ml) of oxalyl chloride in 1 ml of CH2C12 is stirred under N2 at -60C. To this is added a solution of 70 mg (0.065 ml) of dimethylsulfoxide in 0.4 m} of CH2C12, followed by a solution of 200 mg of 5-O-t-butyldi-methylsilyl-23,24-dehydrôavermectin B2a/B2b in 1.2 ml of CH2C12. It is stirred at -60C for 30 min. Then 0.3 ml of triethylamine is added. After 5 minutes the reac~ion mixture is allowed to warm up to room temperature during the next hour. Then the mixture is poured in~o water and extracted with ether. The extract is washed with water, dried, and concentrated in vacuo to a yellow foam. The 5-O-t-butyldimethyl-silyl-23,24-dehydro-4"-oxoavermectin B2afB2b is identified by NMR and mass spectra and u~ed without further purification as s~arting material for chemi~al reactions.
(3~7~:;77 2/DLRll - 31 - 17665IA
Example 10 4" Deoxy-4"-methylamino-5-O~t-bu~yldimethylsilyl-23,24-dehydroavermectin B2a and/or B2b A solution of 200 mg 9f 5-O-t butyldimethyl-silyl-23,24-dehydro-4"-oxo-avermectin B2a/B2b and 190 mg of CH3NH0Ac in 3 ml of MeOH is stirred at room temperature for 15 minu~es. Then 12 mg of NaCNBH3 is added. After 1 hour the reac~ion mixture is poured into aqueous diluted Na2C03 solution. The product is extracted with EtOAc, and the extract is washed with water, dried, and concentrated in vacuo to a yellow foam. The product is purified by preparative silica gel layer chromatography with a CH2C12-MeOH 93:7 solvent mixture, and is identified by NMR and mass spectra as 4"-deoxy-4"-methylamino-5-O-t-butyl-dimethylsilyl-23,24-dehydroavermectin B2a/B2b.
Example 11 4"-Deoxy-4"~me~hylamino-23,24-dehydroavermectin B2a and or B2b A solution of 100 mg of 4"-deoxy-4"-methyl-amino-5-O-t-butyldimethylsilyl-23,24-dehydro-avermectin B2a/B2b and 100 mg of p-toluenesulfonic acid monohydrate in 10 ml of MeOH is stirred at room temperature for 30 minutes, and then poured into dilute aqueous NaHC03 solution. The product is extracted with EtOAc, washed with water and dried over MgSO4, concentrated in vacuo, and purified by preparative silicagel layer chromatography wi~h a CH2C12-MeOH 95:5 ~olvent mixture. It is identi~ied by NMR and mass spectra as 4"-deo~y~ methyl~mino-23,24-dehydroavermectin B2a/B2b.
.
~:~C~76~7 2/DLRll - 32 - 17665IA
5-O-tert-Butyldimethylsilyl-23,24-dehydro-4"-oxoaver-mec~in B2a and/or B2b (4-methyl)semicarbazone.
A solutionof 3.0 ml of MeOH containing 5-O-tert-butyldimethylsilyl-23,24-dehydro-4"-oxo-aver-mectin B~a/B2b S 50 mg ), 4-methylsemicarbazide hydrochloride ( 17 mg ), and sodium acetate ( 15 mg~
is stirred at room temperature for 2 hours. Then addition of 4 ml of water, extraction wi~h ether, washing with water, drying and concentration in vacuo gives the crude product. Purification by preparative silicagel layer chromatography with a CH2C12-MeOH
solvent mixture gives pure 5-0-tert-butyldimethyl-silyl-23,24-dehydro-4"-oxoavermectin B2a and/or B2b (4-methyl~semicarbazone, which is characterized by its mass and lH-NMR spectra.
~ EX~MPLE 13 23,24-Dehydro-4"-oxoavermectin B2a and/or B2b (4-methyl)semicarbazone.
- A solution of 35 mg of 5-0-tert-butyldi-me~hylsilyl-23,24-dehydro-4"-oxoavermectin B2a and/or B2b (4-methyl)s~micarbazone in 3.5 ml of MeOH
containing 1 % of p-toluenesulfonic acid monohydrate is held at room temperature for 60 minutes. Addition of agueous NaHC03 solution, extraction with ether, washing with water, drying and concentration in vacuo gives crude product. Purification by preparative silicagel layer chromatography using a CH2C12-MeOH solvent mix~ure affords pure 23,24-dehydro-4"-oxoavermectin B2a and/or B2b (4 methyl)æemi-carbazone, which is characterized by its mass and lH-NMR spectra.
2~076~
2/DLRll - 33 - 17665IA
10,11-Dihydroavermectin B2a/B2b A solution of 870 mg avermectin B2a/B2b in 25 mL of absolute ethanol and 100 mg of 5% Pd/C was stirred at room t~mperature under one atmosphere pressure of hydrogen. After an uptake of 1.5 molar equivalent of hydrogen, ~he catalyst was removed by filtration. HPLC analysis using a reverse phase C18 column and a methanol-water liquid system indicated lo the composition of the mixture to be 20% avermectin B2a/B2b, 50% 10,11-dihydroavermectin B2a/B2b, 30%
3,4-dihydroavermectin B2a/B2b, and 10% 3,4,10,11-tetrahydroavermectin B2a/B2b. Preparative HPLC using a reverse phase C18 column and a methano-water system gave pure 10,11-dihydro avermectin B2a and/or B2b which was charec~erized by its lH NMR and its mass spectra.
23,24-DehYdro-10,11-dihydroavermectin B2a and~or B2b.
~hen 1.o g of 10,11-dihydroavermectin B2a and/or B2b is reacted consecutively according to the procedurçs fully described in examples 1, 2, 3, 4, and 5, 23,24-dehydro-10,11-dihydroavermectin B2a and/or B2b is obtained, which is charac~erized by its mass and lH-NMR spectra.
S-O-tert-Butyldimethylsilyl-23,2~-dehydro-10,11-dihydro-10-hYdroxYavermectin B2a/B2b.
To a solu~ion of 500 mg of ~-O-tert-butyl-dimethylsilyl-23,24-dehydroavermectin B2afB2b in 10 ~3(~
2/DLRll - 34 17665IA
mL of acetone and 1.0 mL of wa~er is added 110 mg of N-bromoace~amide in one portion. The mixture is stirred in the dark at 20C for 1 h, and worked up by addition of water and extraction wi~h ether or dichloromethane. The solvent i~ removed in vacuo and the residual solid is purified by preparative thick layer silica gel chromatography using a 1:1 hexane :
ethyl acetate solvent system ~o afford crude 5-o-tert-butyldimethylsilyl-ll-bromo-23,24-dehydro-10,11-dihydro-10-hydroxyavermectin ~2a/B~b. This inter-mediate product is dissolved in 6 mL of toluene, and 0.4 mL of tri-n-butyltin hydride is add~d. The mixture i~ heated at 100C under an atmosphere of nitrogen for 2 hours. Column chromatography on silica gel with dichloromethane followed by 1:1 hexane : ethyl acetate provides an initial separation of the product fro~ the tin compounds. Final purifi-cation of the product is achieved by ~PLC on a C-18 reverse phase column using a m0thanol - water liquid phase to afford pure 5-O-tert~butyldime~hylsilyl-23,24-dehydro-10,11-dihydro-10-hydroxyavermectin B2a/B2b, which is characterized by its NMR and mass spectra.
EXAMPLE 17.
5-O-tert-Butyldimethylsilyl-23,24-dehydro-10,11-dihydro-10-hydroxy-4"-O-~rimethylsilylavermec~in B2a~B2b.
To 2.~ g of 5-O-tert-butyldimetAylsilyl~
23,24-dehydro-10,11-dihydro-10-hydroxyavermectin Bla/Blb is added 20 mL of freshly distilled dichloro-methane, 4 mL of (4A sieve-dried) N,N-dimethyl 2/DLRll - 35 - 17665IA
formamide, and 1.O mL of freshly distilled triethyl-amine. To this mixture, after cooling to 0C, is added 0.410 mL of chlorotrimethylsilane. The reaction mixture is stirred at 20C for 2 hours. The reaction mixture is then guenched with 300 mL of water and 60 mL o~ a ~aturated sodium bicarbonat~
~olution. Extraction with dichloromethane and evaporation of the solvent yields the product as a solid. Purification by chromatography on silica gel lo using 3:1 hexane : Et~Ac affords 5-O-tert-bu~yldi-methylsilyl-23,24-dehydro-10,11-dihydro-10-hydroxy-4"-O-trimethylsilylavermectin B2a/B2b which is characterized by its NMR and mass spectra.
EXAMPLE 18.
5-O-tert-Butyldimethylsilyl-23,2~-dehydro-10,11-dihydro-10-fluoroavermectin Bla/Blb.
A solution of 1.68 g of 5-O-tert-butyldi-methylsilyl-23,24-dehydro-10,11-dihydro-10-hydroxy-4"-O-trimethylsilylavermectin 82a/B2b in 20 mL of freshly distilled dichloromethane under ni~rogen is cooled to -78C. To this mixture is added dropwise O.23 mL of diethylaminosulfur trifluoride. After 1 hour at -78C the reaction mixture is quenched with S
mL of a 7% aqueous sodiu~. carbonate ~olution.
Extraction with dichloromethane from the aqueous workup affords a mixtur~ of crude products. This mixture is di~solved in 20 mL o THF : water (9:1) and 125 mg of p-toluenesulfonic acid monohydrate is added in one portion. After exactly 15 min at 20C
the reac~ion i~ quenched by addition of 5 mL of 2 saturated aqueous sodium bicarbonate solution.
Dichlorome~hane extrac~ion of the aqueous workup 2(~:t~77 2/DLRll - 36 - 17665IA
affords the crude product (two major components by TLC analysis). Chromat~graphic purification on silica gel using hexane: ethyl aceta~e (2:1) affords 5-O-tert butyldimethylsilyl-23,24-dehydro-10,11-dihydro-10-fluoroavermectin B2a/B2b and 5-O-tert-butyldimethylsilyl-23,24-dehydro-10,11-dihydro-10-hydroxyavermectin B2a/B2b, which were characterized : by their NMR and mass spectra.
1o EXAMPLE 19.
23,24-Dehydro-10,11-dihydro-10 fluoroavermectin B2a/B2b.
When 5-O tert-butyldimethylsilyl-23,24-dehydro-10,11-dihydro-10-fluoroavermectin B2a/B2b is treated with a solution of anhydrous hydrogen fluoride - pyridine - te~rahydrofuran as fully described in example 5 one obtains 23,24-dehydro-10,11-dihydro~10-fluoroavermectin B2a/B2b which is characterized by its mass spectrum and lH- and 13C-NMR spectra.
5-O-tert-Butyldimethylsilyl-avermectin B2a/B2b aqlYcone.
A ~olution containing 400 mg of avermectin B2a/B2b aglycone (prepared as decribed in Uni~ed States Patent No. 4,206,205) and 544 mg o~ imidazole in 8.0 ml of dimethylformamide was stirred at room temperature until all was in solution. Then 600 mg of tert-butyldimethylsilyl chloride was added in on~
portion and ~he reaction mixture was stirred for an additional 50 minutes at room tempera~ure, when water was added. The rPaction product was isolated by 2~)~j7~;7~
~/DLRll - 37 ~ 17665IA
extraction with ether, washing of the extracts several times with water, then saturated aqueous sodium chloride solution, drying over magnesium sulfate, and concentration to 800 mg of solid residue. Purification by prepara~ive silica gel layer chromatography with 5% tetrahydrofuran in methylene chloride gave 330 mg of 5-O-ter~-butyldi-methylsilyl-avermectin B2a/B2b aglycone, which was characteriz~d by its mass a~d NMR spectra.
S-O-tert-Butyldimethylsilyl-7,13,23-tri-O-trimethYlsilYlavermectin B2a/B2b aql~cone.
A solution of 640 mg of 5-O-tert-butyldimethylsilyl-avermectin B2a/B2b aglycone in 7.5 ml of anhydrous dimethylformamide is stirred at room temperature while 15 ml of bis(trimethylsilyl) trifluoroacetamide is added dropwise. After s~anding an additional 3 hours the reaction mixture is evaporated in high vacuum to a glass, which is characterized by its mass and NMR spectra as 5-O-tert-butyldimethylsilyl-7,13,23-tri-O-trimethyl-sil.ylavermectin B2a/B2b aglycone. The crude product is used for the next step wi~hout further purification.
5-O-tert-Butyldimethylsilyl-7-O-trimethylsilyl-av rmectin B2a/B2b aglycone.
A solution of 354 mg of 5-O-tert-butyl-dimethylsilyl-7,13,23-tri-O-~rimethylsilylavermectin B2a/B2b aglycone in 100 ml of tetrahydrofuran, 15 ml of water, and 8.4 ml of glacial acetic acid is kept at room temperature for 20 hours, when the ~no~7~
2/DLRll - 38 - 17665IA
solution is concentrated in vacuo to a small volume in a water bath of 35C. Water and ethyl acetate are added and the solution made slightly basic with sodium carbonate. The organic phase is separated, dried, and concentrated in vacuo to a light yellow foam, which i~ characterized by its mass and ~MR
spectra as 5-O-tert-butyldimethylsilyl-7-O-trimethylsilylavermectin B2a/B2b aglycone.
5-O-tert-Butyldimethylsilyl-23,24-dehydro-13-deoxy-13-fluoro-7-O-trimethylsilylavermectin B2a/B2b aqlycone.
To a solution of 40 ~L of diethylamino-sulfur trifluoride (DAST) in 1.5 mL of anhydrous methylene chloride stirred at -78C under a blanket of nitrogen, a solut~on of 100 mg of 5-O-tert-butyldi-methylsilyl-7-O-trimethylsilylavermectin B2a/B2b aglycone in 1.5 mL of anhydrous methylene chloride is added dropwise. Subsequently the reaction mixture is kept for 30 minutes at -78C, followed by 6D minutes at -20C, and 90 minutes at room tempPrature. Then dilute aqueous sodium bicarbonate solution is added slowly with ice cooling, and the mixture is extracted with ether, the ether extract is washed with water, dried, and concentrated in vacuo and under high vacuum to a light foam. Purification by preparative silica gel layer chromatography gives 5-O-tert-butyl-dime~hylsilyl-23,24-dehydro-13-deoxy-13-fluoro-7-O-3Q trimethyl~ilylavermectin B2a/B2b aglycone, which ischaracterized by its mass and NMR spectra. This product is obtained as a mixture of ~he ~wo C-13 epimeric 13-alpha- and 13-b~ta fluorocompounds.
37~77 2/DLRll - 39 - 17665IA
23,24-Dehydro-13-deoxy-13-fluoroavermectin B2a/B2b aqlycone. _ _ A solution of 21.6 mg of 5-O-tert-butyldimethylsilyl-23,24 dehydro-l3-deoxy-}3-fluoro-7-O-trimethylsilylavermectin B2a/B2b aglycone in 2.0 mL of an anhydrous hydrogen fluoride - p~ridine-tetrahydrofuran mixture prepared as de~cribed in Example 5 is held at room temperature for 48 hours.
Then the reaction mixture is poured into dilute aqueous sodium bicarbonate sslution and extracted with ethyl acetate, washed with water, dried, and evaporated to a light colored glass. Purification by preparative silica gel layer chromatography gives the two C-13 epimeric 23,24-dehydro-13-deoxy-13-fluoroavermectin B~a/B2b aglycones, which are charac~erized by their mass and NMR spectra.
DESCRIPTION OF THE INVENTION
The compounds of the instant invention have the following structural formula.
C}13 H 22~f ~3 H C' ~ l'H
f 0~5 H 3~ 3 wherein A represents a single bond or a double bond, Rl is iso-propyl or sec-butyl;
R2 is hydroxy, ketone, loweralkoxy, or protected ~ hydroxy;
R3 is hydrogen, halogen, or ketone, however R3 is present only when A represents a single bond;
R4 's hydrogen, hydroxy, halogen, ~0~77 2/DLRll - 6 - 17665IA
R~ ~-- or R~
H,CC~ H3CC~ H,CO
R5 is hydroxy, ketone, -NR6R7 or =NHNC-NR6R7; and R6 and ~7 are independently hydrogen, loweralkyl or loweralkanoyl.
In the instant description, the term "loweralkyl" is intended to include those alkyl groups containing from 1 ~o 6 carbon atom~ in either a straight or branched chain or a cyclic configuration of from 3 to 6 carbon atoms. Exemplary of such alkyl groups are methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, pentyl, hexyl, cyclopentyl, cyclohexyl and the like.
The term "loweralkanoyl" is intended to include those alkanoyl groups of from 2 to ~ carbon atoms of either a straight or branched chain. Such groups are exempli~ied by acetyl, propionyl, butyryl, pentanoyl, hexanoyl and the 1 lkP, The term "halogen" is intended to include the halogen atom, fluorine, chlorine, bromine and iodine.
Preferred compounds of this invention are realized in the above structure wherein:
7~;7t;, 2/DLRll - 7 - l766sIA
A i~ a single, or a double bond; Rl is isopropyl, or sec-butyl; R2 is hydroxy; R3 is hydrogen, halogen, hydroxy or oxo: R4 is hydrogen, hydroxy, halogen, 4'-R5 ~a-L-oleandrosyloxy), 4"-Rs-~4'-(a-L-oleandrosyl)-a-L-oleandrosyloxy]; and R5 is hydroxy, amino, loweralkylamino, diloweralkylamino.
Additional preferred compounds are realized when R4 is halogen, and in particular, when R4 is fluorine, and Rl, R2, R3 and R5 are as defined above.
lo Examples of preferred compounds of this invention are realized in the following:
23,24-dehydro avermectin B2a/B2b " " A2a/A2b ~ B2a/B2b aglycone " " B2a/B2b monosaccharide " -13-deoxy avermectin B2a/B2b aglycone " -10,11-dihydro " B2a/B2b " " " B2a/B2b monosaccharide " " B2a/B2b aglycone " -13-deoxy-10,11-dihydro avermectin B2a/B2b aglycone " -10,11-dihydro-10-fluoro " B2a/B2b " " " " B2a/B2b monosaccharide ~ ~' " " B2a/B2b aglycone ~ -13-deoxy-10,11--dihydro-10-fluoro avermectin B2a/B2b aglycone " 4"-deoxy-4"-methylamino avermect;n B2a~B2b " " 4"-amino " B2a/B2b 4"-dimethylamino " B2a/B2b 4"-oxo avermectin B2a/B2b semicarbazone " l~ ~ B2a/B2b(4-methylsemicarbazone) " " " B2a/B2b~4,4-dimethylsemicarbazone) 23,24-dehydro-13-deoxy-13-fluoroavermectin B2a/B2b aglycone ~:q~ 7~
2/DLRll - 8 - 17665IA
The "b" compounds, those with a 25-iso-propyl group, are somewhat di~ficult to ~eparate from the corresponding "a" compound with a 25-sec-butyl group and as such the compounds are generally isolated as mixtures of the two compounds. Thus references in the instant application to "a"
compounds such as Bla, Ala, and the like, are construed to define the pure compound as well as those which actually contain a certain proportion of the corresponding "b" compound.
Alternatively, this representation of a mixture is sometimes done by referring, for example, to "the Bl or B2 compounds" or by separating the "a"
compound from the "b" compound by a slash (/) such as Bla/Blb, B~a/B2b and the like.
The compounds of the instant invention differ from other avermectin compounds in that the 23-hydr~xy compounds, A2 and B2 compounds are converted into 23-dehydroxy-Q23,24 compounds, Such compounds are significantly superior to the A2 and B2 starting materials in their antiparasitic activity.
The instant compounds are prepared from the suitably protec~ed avermectin A2 or B2 compound, that is a compound with an unprotected 23-hydroxy group but with all other hydroxy groups protected. This compound is treated with the reagent diethylamino sulfurtrifluoride, generally referred to as DAST.
2~30~ 7 2/DLRll - 9 - 17665IA
This reagent is generally known in the art as a fluorinating reagent, however when used under the below described conditions and on the instant compounds, there is observed the surprising result S that no fluoridation occurs anywhere on the avermectin molecule. The unprotected 23-hydroxy group is removed and a 23-24 double bond (a 23,24) is formed.
The reaction is represented in the following reaction scheme.
OH
CH3 22/~ 3 ,~17 ~o~
CH3 ~1 1 1 8 \1~, ~2 0 H
H A o o )7~7~7 2/DLRll -- 10 -- 17665IA
~DAST ~23 H3 CH3 22 `~
R- ~ D~ R~
R3 ~ (I~
~?2 The reaction is carried out initially at a reduced temperature due to the r~activity of D~ST.
Generally temperatures of from -50C to -100C are utilized. It is preferred to carry out ~he reaction at about -78C since this is the temperature which is achieved by placing the reaction vessel in a dry-ice (solid carbon dioxide-acetone) bath. To ~urther avoid side-reactions, the reaction is preerably carried out under a blanket of nitrogen an other inert atmosphere. The reaction is maintained at the reduced temperatures from 10 to 1~0 minutes and then is generally rai~ed to room temperature slowly, over a : period of from 60 to 180 minutes. To complete the 37~77 2/DLRll - ll - 17665IA
reaction, the reaction vessel may be maintained at room temperature for from 1 to 8 hours or until analysis of aliquots of the reaction mixture indicate that the reaction is complete. Generally analy~ical procedures which can follow the disappearance of the 23-hydroxy group will give a good indication of the degree to which the reaction has progressed to completion. The product is isola~ed using standard techniques known to those sXilled in the art and the protecting groups are removed following the procedures described below.
P~EPARATION OF STARTING MATERIALS
The ultimate starting materials for the compounds of this invention are the avermectin fermentation products defined above which have the isopropyl or sec-butyl group at the 25-position.
T~us it is apparent that additional reactions are required to prepare many of the immediate starting materials for the instant compounds. Specifically, reactions are carried out at the ~', 4", 5', 10, ll and 13, positions. In addition, during the various reactions described above, and below it may be necessary ~o protect various reactive groups to prevent the undesired reaction of such groups. In addition, protection of such reactive groups may facilitate ~he separation of the various products.
With the appropriate positions protected, the DAST
reaction may be carried out without affecting the remainder of the molecule. Following the described reactions, the pro~ecting groups may be removed and the unprotected product isolated. The protecting 2(~ 7~77 2/DLRll - 12 - 17S65IA
group employed is ideally one which may be readily synthesized, will not be affected by the reaction with the various reagents employed and may be readily removed without affecting any other functions of the molecule. It is noted that the instant protected compounds are novel and have considerable antiparasitic activity. They are included within the ambit of the instant invention. One preferred type of protecting group for the avermectin type of molecule is the tri-substituted silyl group, preferably the trialkyl silyl group. One especially preferred example, is the t-butyl dimethylsilyl group. The reaction preparing the protected compound i5 carried out by reactiny a hydroxy compound with the appropriately substituted silylhalide, preferably the silylchloride in an aprotic polar solvent such as dimethylformamide. Imidazole is added as a catalyst. The reaction is complete in from 1 to 24 hours at from 0 to 25C. For the 5-position hydroxy group the reaction is complete in from 1/2 to 3 hours at from 0C to room temperature. This reaction is selective to the 5 position under the conditions above described and very little, if any, silylation is observed at other hydroxy substituted positions.
The silyl groups are then removed after the other reactions have been carried out. The silyl group or groups are remo~ed by stirring the silyl compound in methanol catalyzed by a catalytic ~mount of an acid, preferably a sulfonic acid such as p-toluene sulfonic acid. The reaction is complete in about 1 to 12 hours at from 0 to 50C. Alternatively, the silyl group or groups can be removed with a hydro-2~")~t~
2/DLRll - 13 - 17665IA
gen fluoride-pyridine complex in an organic solvent such as tetrahydrofuran. The reaction is complete in from about 3 ~o 24 hours and is preferably carried out at room temperature.
Additional reactions which may be carried out to prepare the compounds of ~his invention are the selective removal of one of the a-L-oleandrosyl moieties (described in U.S. Paten~ 4,206,205 to Mrozik et al.).
lo The reaction conditions which are generally applicable to the preparation of both the mono-saccharide and aglycone involve dissolving ~he avermectin compound or the hydrogenated avermectin compound in an aqueous acidic non-nucleophilic lS organic solvent, miscible with water, preferably dioxane, tetrahydrofuran, dimethoxyethane, dimethyl formamide, bis-2-methoxye~hyl ether, and the like, in which the water concentration is from 0.1 to 20~ by volume. Concentrat~d sulfuric acid is added to the aqueous organic solvent to the extent of 0.01 to 10%
by volume. Th~ reaction mixture is generally stirred at about 20-40C, preferably at room temperature, or from 6 to 24 hours. The lower conc ntration of acid, from about 0.01 to 0.1% will predominately produce the monosaccharide under ~he above reaction conditions. Higher acid concentrations, from about 1 to 10% will predominantly produc~ the aglycone under the above reaction conditions. Intermediate acid concentratiQns will generally produce mixtures of monosaccharide and aglycone. The products are isolated, and mixtures are separated by ~echnigues 2(~7~7~
2/DLRll - 14 - 17665IA
such as column, thin layer preparative and high pressure li~uid chromatography, and other known techniques.
The acids which may be employed in the above process include mineral acids and organic acids such as sulfuric, hydrohalic, phosphoric, trifluoroacetic, trifluoro methane sulfonic and the like. The hydro-halic acids are preferably hydrochloric or hydro-bromic. The preferred acid in the above process is sulfuric acid.
A further procedure for the preparation of the monosaccharide or aglycone of the avermectin compounds or of the hydrogenated avermectin compounds utilizes a different solvent system for ~he mono-saccharide and the aglycone. ThP procedure for the preparation of the monosaccharide uses 1% acid by volume in isopropanol at from 20-40C, preferably room temperature, for from 6 ~o 24 hours. For ~he preparation of the aglycone, 1% acid, by volume, in methanol under the foregoing reac~ion condi~ions has been found to be appropriate.
Any strong inorganic or organic acid is appropria~e for this process, and again sulfuric acid is the preferred acid.
It has also been observed that the mono-saccharide is prepared during the course of the reackion used to remove the trialkylsilyl protecting group. Since acid catalysis is used to remove the pro~ecting group, ~his is expected. However, in such cases, both the desired product and the monQsaccharide are prepared and they can be readily separated using the above-described ~echniques.
7~7 2/DLRll - 15 - 17665IA
In thP preparation of the 4' or 4" keto or amino substituted compounds, the avermectin startin~
materials are oxidized at the 4' or 4"-position to the corresponding keto compound. The procedures for the preparation of such compounds are described in U.S. Patent 4427663 to Mrozik. During the procedure the presence of any hydroxy groups at the 5 and 23-position will require tha~ such hydroxy groups be protecte~ in order that they too are not oxidized.
The 7-hydroxy group is very unreactive and need not be protected. The procedure used to prepare the protected intermediates are described above. The oxidation reaction is carried ou~ in an inert solvent such as methylene chloride using oxalyl chloride or trifluoroacetic anhydride with dimethylsulfoxide as the oxidizing agent. The reaction proceeds by dissolving the oxalyl chloride or trifluoroacetic anhydride and dimethylsulfoxide (or other oxidizing reagents3 in methylene chloride cooled to fro~ -50 to -80C and adding dropwise a methylene chloride solution of the avermectin compound to be oxidized, The addition is carried out over a period of ~rom 15 minutes to 1 hour and then trie~hylamine is added dropwise over a period of from 1 to 15 minutes. The reaction mixture is then allowed to warm to room temperature over a period of from 1/2 to 1 hour. The 4' or 4"-keto compound is isolated using techniques known to those skilled in the art.
In the next step, the 4' or 4"-keto compound is aminated to prepare the unsubstituted amino compound (R6=R7=hydrogen). The reaction is carried OU't in an inert solvent such as methanol at from -10 37~7~
2/DLRll - 16 - 17665IA
to +25OC usiny ammonium salts and sodium cyanoboro-hydride as the aminating and reducing reagents, respectively. The reaction is complete in from 15 minutes to 24 hours and the product 4"-deoxy 4"-amino compound is isolated using techniques known to those skilled in the art. Sui~able ammonium salts are the acetate, propionate, benzoate and the like. The acetate is preferred.
As a variation to the foregoing amination reac~ion, m~hyl ammonium salts can be used in place of the ammonium salts to prepare the monomethyl substituted compound directly. The same reagents, salts and reaction conditions as described above can be used for such a reaction.
The substitution reaction wherein the substituent is an acyl function is carried out using an acylating reagent in the presence of a base in an inert solvent~ The acylation of avermec~in compounds, is fully described in U.S. Patent 4201861 to Mrozik et al~ The preferred acylating reagents are loweralkanoyl anhydrides, loweralkanoyl halides, substituted benzene sulfonyl chlorides, lower alkyl sulfonyl chlorides, and the like~ The reaction is carried out in an inert solvent such as methylene chloride in the presence of a non-reactive base such as pyridine or triethylamine in ~rder to neutralize the acid produced during the course of the rea~tion.
The reaction temperature is from -10 ~o ~5C and the reaction is complete in from 5 minutes to 8 hours.
The product is isolated using known technigues~
The reaction for the preparation of the 4'-or 4"-deo~y-4'- or ~"-dialkylamino compounds is ~0~6~)~
2/DLRll - 17 - 176~5IA
carried out using the alkylating reaction conditions of an exce6s of a carbonyl compound, preferably formaldehyde and a reducing agent such as sodium cyano borohydride, in methanol. The reaction is carried out in a solvent suitable to dissolve the organic starting material using excess aqueous formaldehyde along with the presence of a small amount of acid such as acetic acid to facilitate the reaction. The reaction is carried out at from 10 to ~25C with the solution of the avermectin compound in methanol added dropwise over a period of from 30 to 60 minutes to the alkylating reagent mixture and the product is isolated using known techniques.
Further reactions of the avermectin compounds either before or after the DAST reaction are possible to prepare the compounds of this invention.
~ Following the preparation of the aglycone (R4 is hydroxy at the 13 position), U.S. Patents Re 32006 and Re 32034 to Chabala et al. disclose the hydroxy group displacement with a halogen using a reagent such as benzene sulfonylhalide, and the halogen is removed by reduction using a reducing agent such as trialkyltin hydride.
The hydroxy group at 5 may be alkylated following the procedures described in U.S. Patent 4200581 to Fisher et al.
The novel compounds of ~his inv~ntion have significant parasiticidal activity as anthelmintics, ectoparasiticides, insecticide~ and acaricides, in human and animal health and in agriculture.
The disease or group of diseases described generally as helminthiasis is due to infection of an 2~07fi7~
2/DLRll - 18 - 17665IA
animal host with parasitic worms known as helminths.
Helminthiasis is a prevalent and serious economic problem in domesticated animals such as swine, sheep, horses, cattle, goats, dogs, cats and poultry. Among the helminths, the group of worms described as nematodes causes widespread and often times serious infection in various species of animals. The most common genera of nematodes infecting the animals referred ~o above are Haemon~hus, TrichostronqYlus, Ostertaqia, Nematodirus, Cooperia, Ascaris, Bunostomum, OesoPhaqostomum~ Chabertia, Trichuris, Stronqylus, Trichonema, DictYocaulus, CaPillaria, Heterakls, Toxocara, Ascaridia, OxYuris, AncYlostoma, Uncinaria, Toxascaris and Parascaris. Certain of these, such as Nematodirus, Cooperia and Oesophaqostomum attack primarily the intestinal tract while others, such as Haemonchus and Os~ertaqia, are more prevalent in the stomach while still others such as Dictyocaulus are found in the lungs. Still other parasites may be located in other tissues and organs of the body such as the heart and blood vessels, subcutaneous and lymphatic tissue and the like. The parasitic infections known as helminthiases lead to anemia, malnutrition, weakness, weight loss, severe damage to the walls of the intestinal tract and other tissues and organs and, if left untreat~d, may result in death of the infected host. The substituted avermectin compounds of this invention have unexpectedly high activity against the~e parasites, 3~ and in addition are also active against Dirofilaria in dogs, Namatospiroides, SyPhacia, AsPiculuris in rodents, arthropod ectopara ites of animals and birds Z(~f.`~
2/DLRll - 19 - 17665IA
such as ticks, mites, lice, fleas, blowfly, in sheep Lucilia sp., biting insects and such migrating diperous larvae as HYpoderma sp. cattle, GastroPhilus in hor~es, and Cuterebra sp. in rodents.
The instant compounds are also useful against parasites which infect humans. The most common genera of paxasites of the gastro-intestinal tract of man are AncYlostoma, Necator, Ascaris, StronqYloides, Trichinella, Ca~illaria, Trichuris, and Enterobius.
Other medically important genera of parasites which are found in the blood or other tissues and or~ans outside the gastrointestinal tract are the filiarial worms such as Wuchereria, Bruqia, Onchocerca and Loa, Dracunculus and extra intestinal stages of the intestinal worms Stronqyloides and Trichinella. The compounds are also of value against arthropods parasitizing man, biting insects and other dipterous pests causing annoyance to man.
The compounds are also active against house-hold pests such as the cockroach, Blatella sP., clothes moth, Tineola sp., carpet beetle, Attaqenus sP., and the housefly Musca domestica.
The compounds are also useful against insect pes~s of stored grains such as Tribolium sP., Tenebrio sp. and of agricultural plants such as two-spotted spider mites, (Tetranychus sP.), aphids, ~AcYrthiosiphon sp.); against migratory orthopterans such as locusts and immature stages of insects living on plant tissue. The compounds are useful as a nematocide for the control of soil nematodes and plant parasites such as Meloidoqyne ~E~ which may be of importance in agriculture The compounds are ~0~:~'7677 2~DLRll - 20 - 17665IA
active against other plant pests such as the southern army worm and Mexican bean beetle larvae.
These compounds may be administered orally in a unit dosage form such as a capsule, bolus or 5 tablet, or as a liquid drench where used as an anthelmintic in mammals. The drench is normally a solution, suspension or dispersion of the active ingredient usually in water ~ogether with a sus-pending agent such as bentonite and a wetting agent or like excipient. Generally, the drenches also contain an antifoaming agent. Drench formulations generally contains from about 0.001 to 0.5% by weight of the active compound, Preferred drench formula-tions may contain from 0.01 to 0.1% by weight. The capsules and bo}uses comprise the active ingredient admixed with a carrier.vehicle such as starch, talc, magnesium stearate, or di-calcium phosphate.
- Where it is desired to administer the avermectin derivatives in a dry, solid unit dosage form, capsules, boluses or tablets containing the dçsirPd amount of active compound usually are em-ployed. These dosage forms are prepared by inti-ma~ely and uniformly mixing ~he active ingredient with suitable finely divided diluents, fillers, disinte~rating agents and/or binders such as starch, lactose, talc, magnesium steara~e, vegetable gums and the like. ~uch uni~ dosage formulationæ may be varied widely with respec~ to their total weight and content of ~he antiparasitic agent depending upon factors such as the ~ype of host animal to be treated, the severity and type of infection and the weight of the host.
)7~'7 2/DLRll - 21 - 17665IA
When the active compound is to be adminis-tered via an animal feedstuff, it is intimately dispersed in the feed or used as a top dressing or in the form of pellets which may then be added to the finished feed or optionally fed separately. Alterna-tiv~ly, the antiparasi~ic compounds of our invention may be administered to animals parPntPrally, ~or example, by intraruminal, intramuscular, intra-tracheal, or subcutaneous injection in which event the active ingredient is dissolved or dispersed in a li~uid carrier vehicle. For parenteral adminis-tration, the active material is suitably admixed with an acceptable vehicle, preferably of the vegetable oil variety such as peanut oil, cotton seed oil and the like. Other parenteral vehicles such as organic preparation using solketal, glycerol formal, and aqueous parenteral formulations are also used. The active avermectin compound or compounds are dissolved or suspPnded in the parenteral formulation for administration; such formulations generally contain from 0.005 to 5% by weight of the active compound.
Although ~he antiparasitic agents of this in~ention find their primary use in the tr~atment and/or prevention of helminthiasis, they arP also useful in the prevention and treatment of diseases caused by other parasites, for example, arthropod parasites such as ticks, lire, fleas, mites and other biting insects in domesticated animals and poultry.
They are also effective in treatment of parasitic diæeases that occur in other animals including humans. The optimum amount to be employed for best results will, of course, depend upon the particular '76~7 2/DLRll - 22 - 17665IA
compound employed, the species of animal to be treated and the type and severi~ of parasitic infection or inf estation. Generally good results are ob~ained with our novel compounds by the oral administration of from about 0.001 to 10 mg per kg of animal body weight, such total dose being given at one time or in divided doses over a relatively short period of time such as 1-5 days. With the preferred compounds of the invention, excellent control o~ such parasites is obtained in animals by administering from about 0.025 to 0.5 mg per kg of body weight in a single dose. Repeat tr~atments are given as required to combat re-infections and are dependent upon the species of parasite and the husbandry techniques being employed. The techniques for administering these materials to animals are known to those skilled in the veterinary field.
~ hen the compounds des~ribed herein are administered as a component of the feed of the animals, or dissolved or suspended in the drinking water, compositions are provided in which the active compound or compounds are intimately dispersed in an inert carrier or diluent. By inert carrier is meant one that will not react with the antiparasitic agent and one that may be administered safely to animals.
Preferably, a carrier for feed administration is one that is, or may be, an ingredient of the animal ration.
~uitable composi~ions include feed premixes or supplements in which the active ingredient is present in relatively large amounts and which are suitable for direct feeding to ~he animal or for 2~ 7~;77 2/DLRll - 23 - 17665IA
addition to the feed either directly or after an intermediate dilution or blending step. Typical carriers or diluents suitable for such compositions include, for example, distillers' dried grains, corn meal, citrus meal, fermentation residues, ground oyster shells, wheat shorts, molasses solubles, corn cob meal~ edible bean mill feed, soya grits, crushed limestone and the like. The active compounds are intimately dispersed throughout the carrier by methods such as grinding, stirring, milling or tumbling. Compositions containing from about 0.005 to 2.0~ by weight of the active compound are particu-larly suitable as feed premixes. ~eed supplements, which are fed directly to the animal, contain from about 0.0002 to 0.3~ by weight of the active com~
pounds.
Such supplements are added to the animal feed in an amount to give the finished feed the concentration of active compound desired for ~he treatment and control of parasitic diseases.
Although ~he desired concPntration of active compound will vary depending upon the factors previously mentioned as well as upon ~he particular avermectin derivative employed, the compounds o~ this invention are usually fed at concentrations of be~ween 0.00001 to 0.002% in the feed in order to achieve the desired antiparasi~ic result.
The avermectin compounds of this invention are also useful in combatting agricultural pests that inflict damage upon crops while they are growing or while in storage. The compounds are applied using known teohnigues as sprays, dus~s, emulsions and thP
~:~3~
2/DLRll - 24 - 17665~A
like, to the growing or stored crops to effect protection from such agricultural pests.
In using the compounds of this invention, the individual substitutPd avermectin components may be prepared and used in that form. Alternatively, mixtures of two or more of the individual avermectin components may be used, as well as mixtures o the parent avermectin compounds, other avermectin compounds or o~her ac~ive compounds not related to avermectin, wi~h the compounds of this invention.
In the isolation of the avermectin compounds, which serve as starting materials for the instant processes, from the fermentation broth, the various avermectin compounds will be found to have lS been prepared in unequal amounts. In particular an "a" series compound will be prepared in a higher proportion than the corresponding "b" series compound.
The difference between the "a" series and "b" series is constant throughout t~e avermectin compounds and consists of a sec-bu~yl group and an iso-propyl group respectively at the 25 position. This difference, of course, does not interfere with any of the ins~ant reactions. In particular it may not be necessary to separate the "~" components from the related "a"
component. Separation of these closely rela~ed compounds is generally not practiced æince the "b"
compound is present only in a small percent by w~ight, and the structural difference has negligible effect on the reaction processes and biological activities.
In par~icular it has been found that the starting materials for ~hP compounds of this inven-tion are very often prepared in a ratio of about 80 Z(-~C)7'67'~
2/DLRll - 25 - 17665IA
avermectin Bla or Ala and 20% avermectin Blb or Alb.
Thus the preferred composition of this invention is one which contains about 80% of the "a" component ~nd 20% of ~he "b" componen~.
The following examples are provided in order that this invention might be more fully understood;
they are not to be construed as limitative of the invention.
The substitu~ed avermectin derivatives lo prepared in the following examples are generally isolated as amorphous solids and not as crystalline solids. They are thus characterized analytically using techniques such as mass spectrometry, nuclear magnetic resonance, and the like. Being amorphous, the compounds are not characterized by sharp melting points, however, the chroma~ographic and analytical methods employed demonstrate the puri~y of the compounds.
In the following examples, the various starting materials therefor are avermectin compounds or derivatives of avermectin c~mpounds. The avPr-mectin compounds and the preparation and isola~ion thereof from fermentation broths are described in United S~ates Patent No. 4,310,519 issued 12 January 1982. The 22,23-dihydro derivatives of avermectin compounds are described in U.S. Patent 4,199,5~9.
The aglycone and monosaccharide derivatives o~
avermectin compounds are described in U. æ . Patent 4,~06,205. The 13-deoxy ~ompounds are described in U.S. Patents R~ 32006 and Re 32034.
~3~ 677 Z/DLRll - 26 - 17665IA
The 4' and 4" amino compounds are described in U.S.
Patent 4,427,6~3. The acyl derivatives are disclosed in U.S. Patent 4201861. The epoxide derivatives are disclosed in U.S. Patent 4,530,971. The 13-keto and amino compounds are disclosed in U.S. Patent 4,579,864, and the o-alkyl compounds are disclosed in U.S. Patent 4,200,581. The 13-(alkoxy)methoxy compounds are disclosed in U.S. Patent 4,587,247.
The following examples are being provided in order that the invention may be more fully understood.
They are not to be construed as being limitative of the invention.
4",5-Di-O-tert-butyldimethylsilyl-avermectin B2a and/or B2b _ _ _ A solution of 1.0 g of avermectin B2a and/or B2b, 0.614 g of imidazole, 0.680 mg of tert-butyl-dimethylsilyl chloride in 12.3 ml of anhydrous DMF
was stirred at room temperature under N2 for 20.5 hours. Then water and ether were added, the organic phase separated, washed repeatedly with water and concentrated in vacuo. Puxification by silica gel column chromatography gave 401 mg of 4",5,23-tri-O-~ert-butyldimethylsilyl-avermectin B2a and/or B2b, ~37 mg of the desired 4",5-di-O-tert-butyldimethyl-6ilyl-avermectin B2a and/or B2b, 11~ mg of 5,23-di-O-t:ert-butyldimethylsilyl-~vermectin B2a and~or B2b, and 129 mg of 5-O-tert-butyldimethylsilyl-avermectin B2a and/or B2b, all of which were charac~erized by their mass and/or ~H-NMR spectra.
2/DLRll - 27 - 17665IA
4",5-Di-O-tert-butyldimethylsilyl-7,23-di-O-trimethylsilYl avermectin B2a and/or B~b To a solution containing 100 mg of 4",5-di-O-tert-butyldimethylsilyl-avermectin B2a and/or B2b in 0.5 ml of anhydrous DMF 1.O ml ~f bis~trimethylsilyl)trifluoroacetamide was added dropwise. The reaction mixture was held 3 hours at room temperature and then evaporated in vacuo and high vacuum to a glass. This was shown to be more than 90 % pure and assigned the structure of 4",5-di-O-tert-butyldimethylsilyl-7,23-di-O-tri-methylsilyl avermectin B2a and/or B2b in analogy to similar reactions. The crude product was used immediately for ~he next step.
4",5-Di-O-tert-butyldimethylsilyl-7-O-trimethylsilyl avermectin B2a and/or B2b _ A solution of 480 mg of 4",5-di-O-tert-butyldimethylsilyl-7~23-di-O-trimethylsilyl avermectin B2a and/or B2b in 100 ml of THF, 15 ml of water, and ~.4 ml of glacial acetic acid was held at room ~emperature for 20 hours. Th~n the reaction mixture was concentrated to a ~maller volume in high vacuum at room temperature. Water and EtOAc were added, and the solution was made slightly ba~ic with NaHC~3. The organic phase was separated and worked up to give 460 mg of a light yellow foam, which was characterized by its mass and lH-NMR spectra as 4",5-di-O-tert-butyldimethylsilyl-7-O tri-methylsilyl avermectin B2a and/or B2b.
æ~ 67 ~
4",5-Di-O-tert-butyldimethylsilyl-7-O-trimethylsilyl-23,24-dehYdroa~ermectin B2a and/or B2b To a solution of 13.3 microL of diethyl-aminosulur trifluoride (DAST) in 0.5 ml of anhydrousCH2C12 stirred at minus 78C under N2 was added a solution of 100 mg of 4",5-di-O-tert-butyldimethyl-silyl-7-O-trimethylsilyl avermectin B2a and/or B2b in 0.5 ml of anhydrous CH2C12. The reaction mixture was held 30 minutes at minus 78~C, followed by 60 minutes at minus 20C and 90 minutes at room temperature. The reaction product was isolated by addition of dilute NaHCO3 solution and extraction with ether giving 87 mg of light colored foam. TLC analysis showed at least three reaction products. Purification by preparative silicagel layer chromatography ga~e 33 mg of a pure sample as white foam which was assigned the structure of 4",5-di-O-tert-butyldimethylsilyl-7-O~
trimethylsilyl-23,24-dehydroavermectin B2a and/or B2b by its mass and lH-NMR spectra. The structure was confirmed by further spectral investigation of the deprotected compound.(See Example 5).
23,24-DehYdroavermectin ~2a and/or B2b A solution of 33 mg of 4",5-di-O-tert-butyldimethylsilyl-7-O-trimethylsilyl-23,24-dehydro-avermectin B2a and/or B2b in 2.0 ml of an anhydrous hydrogen fluoride - pyridine - tetrahydrouran ~o mixture, prepared by mixing 14.0 ml of THF, 4.0 ml of pyridine and 2.0 ml of commercial HF - pyridine (consisting of 70 % HF and 30 ~ of pyridine, supplied by Aldrich Chemical Company) was kept at room ~ ~ O 7 ~ ~7 2/DLRll - 29 - 17665IA
temperature for two days. Then the reaction mixture was poured into dilute aqueous sodium bicarbonate ~olution and extracted with EtOAc to give 27 mg of 23,24-dehydroavermectin B2a and/or B2b as a glass, which was fully characterized by its W ~pectrum, EI
and FAB ma~s spec~ra, and lH-, and 13C-NMR spectra includin~ lH-"COSY" and 13C-APT.
23,24-Dehydroavermectin A2a and/or A2b When avermectin A2a and/or A2b is reacted in accordance to the procedures described in examples 1, 2, 3, 4, and 5, 23,24-dehydroavermectin A2a and/or A2b is obtained, which can be characterized by its mass spectrum and lH-, and 13C-NMR spectra.
~3,24-Dehydro-13-deoxyavermectin B2a and/or B2b aqlYcone When 13-deoxyavermectin B2a and/or B2b aglycone is reac~ed in accordance to the procedures described in examples 1, 2, 3, 4, and 5, then 23,24-dehydro-13-deoxyavermectin B2a and/or B~b aglycone is obtained, which can be characterized by its mass spectrum and lH-, and 13C-NMR spectra.
Exam~le 8 5-O-t-Butyldimethylsilyl-23, 24-dehydroavermect in B2a and/or B2b . . .
A solution of 130 mg of 23,2~-dehydro-avermectin B2a, 68 mg of imidazole, and ~1 mg of tert-butyldimethylsilyl chloride in 1.5 ml of DMF is ~n(~7~
2/DLRll - 30 - 17665IA
stirred at room temperature for 45 min. The reaction mixture is then poured into water. The product is extracted with ether; the extrac~ is washed with water, dried and concentrated in vacuo to a light foam. Purification by preparative ~ilica gel thin layer chromatography with CH2C12-EtOAc 85:15 solvent mixture gives 5-O-t-bu~yldimethylsilyl 23,24-dehydroavermectin B2a and/or B2b, which is characterized by NMR and mass spec~ra.
ExamPle 9 5-O-t-Butyldimethylsilyl-23,24-dehydro-4"-oxoaver-mectin B2a and/or B2b A solution of 57 mg (0.04 ml) of oxalyl chloride in 1 ml of CH2C12 is stirred under N2 at -60C. To this is added a solution of 70 mg (0.065 ml) of dimethylsulfoxide in 0.4 m} of CH2C12, followed by a solution of 200 mg of 5-O-t-butyldi-methylsilyl-23,24-dehydrôavermectin B2a/B2b in 1.2 ml of CH2C12. It is stirred at -60C for 30 min. Then 0.3 ml of triethylamine is added. After 5 minutes the reac~ion mixture is allowed to warm up to room temperature during the next hour. Then the mixture is poured in~o water and extracted with ether. The extract is washed with water, dried, and concentrated in vacuo to a yellow foam. The 5-O-t-butyldimethyl-silyl-23,24-dehydro-4"-oxoavermectin B2afB2b is identified by NMR and mass spectra and u~ed without further purification as s~arting material for chemi~al reactions.
(3~7~:;77 2/DLRll - 31 - 17665IA
Example 10 4" Deoxy-4"-methylamino-5-O~t-bu~yldimethylsilyl-23,24-dehydroavermectin B2a and/or B2b A solution of 200 mg 9f 5-O-t butyldimethyl-silyl-23,24-dehydro-4"-oxo-avermectin B2a/B2b and 190 mg of CH3NH0Ac in 3 ml of MeOH is stirred at room temperature for 15 minu~es. Then 12 mg of NaCNBH3 is added. After 1 hour the reac~ion mixture is poured into aqueous diluted Na2C03 solution. The product is extracted with EtOAc, and the extract is washed with water, dried, and concentrated in vacuo to a yellow foam. The product is purified by preparative silica gel layer chromatography with a CH2C12-MeOH 93:7 solvent mixture, and is identified by NMR and mass spectra as 4"-deoxy-4"-methylamino-5-O-t-butyl-dimethylsilyl-23,24-dehydroavermectin B2a/B2b.
Example 11 4"-Deoxy-4"~me~hylamino-23,24-dehydroavermectin B2a and or B2b A solution of 100 mg of 4"-deoxy-4"-methyl-amino-5-O-t-butyldimethylsilyl-23,24-dehydro-avermectin B2a/B2b and 100 mg of p-toluenesulfonic acid monohydrate in 10 ml of MeOH is stirred at room temperature for 30 minutes, and then poured into dilute aqueous NaHC03 solution. The product is extracted with EtOAc, washed with water and dried over MgSO4, concentrated in vacuo, and purified by preparative silicagel layer chromatography wi~h a CH2C12-MeOH 95:5 ~olvent mixture. It is identi~ied by NMR and mass spectra as 4"-deo~y~ methyl~mino-23,24-dehydroavermectin B2a/B2b.
.
~:~C~76~7 2/DLRll - 32 - 17665IA
5-O-tert-Butyldimethylsilyl-23,24-dehydro-4"-oxoaver-mec~in B2a and/or B2b (4-methyl)semicarbazone.
A solutionof 3.0 ml of MeOH containing 5-O-tert-butyldimethylsilyl-23,24-dehydro-4"-oxo-aver-mectin B~a/B2b S 50 mg ), 4-methylsemicarbazide hydrochloride ( 17 mg ), and sodium acetate ( 15 mg~
is stirred at room temperature for 2 hours. Then addition of 4 ml of water, extraction wi~h ether, washing with water, drying and concentration in vacuo gives the crude product. Purification by preparative silicagel layer chromatography with a CH2C12-MeOH
solvent mixture gives pure 5-0-tert-butyldimethyl-silyl-23,24-dehydro-4"-oxoavermectin B2a and/or B2b (4-methyl~semicarbazone, which is characterized by its mass and lH-NMR spectra.
~ EX~MPLE 13 23,24-Dehydro-4"-oxoavermectin B2a and/or B2b (4-methyl)semicarbazone.
- A solution of 35 mg of 5-0-tert-butyldi-me~hylsilyl-23,24-dehydro-4"-oxoavermectin B2a and/or B2b (4-methyl)s~micarbazone in 3.5 ml of MeOH
containing 1 % of p-toluenesulfonic acid monohydrate is held at room temperature for 60 minutes. Addition of agueous NaHC03 solution, extraction with ether, washing with water, drying and concentration in vacuo gives crude product. Purification by preparative silicagel layer chromatography using a CH2C12-MeOH solvent mix~ure affords pure 23,24-dehydro-4"-oxoavermectin B2a and/or B2b (4 methyl)æemi-carbazone, which is characterized by its mass and lH-NMR spectra.
2~076~
2/DLRll - 33 - 17665IA
10,11-Dihydroavermectin B2a/B2b A solution of 870 mg avermectin B2a/B2b in 25 mL of absolute ethanol and 100 mg of 5% Pd/C was stirred at room t~mperature under one atmosphere pressure of hydrogen. After an uptake of 1.5 molar equivalent of hydrogen, ~he catalyst was removed by filtration. HPLC analysis using a reverse phase C18 column and a methanol-water liquid system indicated lo the composition of the mixture to be 20% avermectin B2a/B2b, 50% 10,11-dihydroavermectin B2a/B2b, 30%
3,4-dihydroavermectin B2a/B2b, and 10% 3,4,10,11-tetrahydroavermectin B2a/B2b. Preparative HPLC using a reverse phase C18 column and a methano-water system gave pure 10,11-dihydro avermectin B2a and/or B2b which was charec~erized by its lH NMR and its mass spectra.
23,24-DehYdro-10,11-dihydroavermectin B2a and~or B2b.
~hen 1.o g of 10,11-dihydroavermectin B2a and/or B2b is reacted consecutively according to the procedurçs fully described in examples 1, 2, 3, 4, and 5, 23,24-dehydro-10,11-dihydroavermectin B2a and/or B2b is obtained, which is charac~erized by its mass and lH-NMR spectra.
S-O-tert-Butyldimethylsilyl-23,2~-dehydro-10,11-dihydro-10-hYdroxYavermectin B2a/B2b.
To a solu~ion of 500 mg of ~-O-tert-butyl-dimethylsilyl-23,24-dehydroavermectin B2afB2b in 10 ~3(~
2/DLRll - 34 17665IA
mL of acetone and 1.0 mL of wa~er is added 110 mg of N-bromoace~amide in one portion. The mixture is stirred in the dark at 20C for 1 h, and worked up by addition of water and extraction wi~h ether or dichloromethane. The solvent i~ removed in vacuo and the residual solid is purified by preparative thick layer silica gel chromatography using a 1:1 hexane :
ethyl acetate solvent system ~o afford crude 5-o-tert-butyldimethylsilyl-ll-bromo-23,24-dehydro-10,11-dihydro-10-hydroxyavermectin ~2a/B~b. This inter-mediate product is dissolved in 6 mL of toluene, and 0.4 mL of tri-n-butyltin hydride is add~d. The mixture i~ heated at 100C under an atmosphere of nitrogen for 2 hours. Column chromatography on silica gel with dichloromethane followed by 1:1 hexane : ethyl acetate provides an initial separation of the product fro~ the tin compounds. Final purifi-cation of the product is achieved by ~PLC on a C-18 reverse phase column using a m0thanol - water liquid phase to afford pure 5-O-tert~butyldime~hylsilyl-23,24-dehydro-10,11-dihydro-10-hydroxyavermectin B2a/B2b, which is characterized by its NMR and mass spectra.
EXAMPLE 17.
5-O-tert-Butyldimethylsilyl-23,24-dehydro-10,11-dihydro-10-hydroxy-4"-O-~rimethylsilylavermec~in B2a~B2b.
To 2.~ g of 5-O-tert-butyldimetAylsilyl~
23,24-dehydro-10,11-dihydro-10-hydroxyavermectin Bla/Blb is added 20 mL of freshly distilled dichloro-methane, 4 mL of (4A sieve-dried) N,N-dimethyl 2/DLRll - 35 - 17665IA
formamide, and 1.O mL of freshly distilled triethyl-amine. To this mixture, after cooling to 0C, is added 0.410 mL of chlorotrimethylsilane. The reaction mixture is stirred at 20C for 2 hours. The reaction mixture is then guenched with 300 mL of water and 60 mL o~ a ~aturated sodium bicarbonat~
~olution. Extraction with dichloromethane and evaporation of the solvent yields the product as a solid. Purification by chromatography on silica gel lo using 3:1 hexane : Et~Ac affords 5-O-tert-bu~yldi-methylsilyl-23,24-dehydro-10,11-dihydro-10-hydroxy-4"-O-trimethylsilylavermectin B2a/B2b which is characterized by its NMR and mass spectra.
EXAMPLE 18.
5-O-tert-Butyldimethylsilyl-23,2~-dehydro-10,11-dihydro-10-fluoroavermectin Bla/Blb.
A solution of 1.68 g of 5-O-tert-butyldi-methylsilyl-23,24-dehydro-10,11-dihydro-10-hydroxy-4"-O-trimethylsilylavermectin 82a/B2b in 20 mL of freshly distilled dichloromethane under ni~rogen is cooled to -78C. To this mixture is added dropwise O.23 mL of diethylaminosulfur trifluoride. After 1 hour at -78C the reaction mixture is quenched with S
mL of a 7% aqueous sodiu~. carbonate ~olution.
Extraction with dichloromethane from the aqueous workup affords a mixtur~ of crude products. This mixture is di~solved in 20 mL o THF : water (9:1) and 125 mg of p-toluenesulfonic acid monohydrate is added in one portion. After exactly 15 min at 20C
the reac~ion i~ quenched by addition of 5 mL of 2 saturated aqueous sodium bicarbonate solution.
Dichlorome~hane extrac~ion of the aqueous workup 2(~:t~77 2/DLRll - 36 - 17665IA
affords the crude product (two major components by TLC analysis). Chromat~graphic purification on silica gel using hexane: ethyl aceta~e (2:1) affords 5-O-tert butyldimethylsilyl-23,24-dehydro-10,11-dihydro-10-fluoroavermectin B2a/B2b and 5-O-tert-butyldimethylsilyl-23,24-dehydro-10,11-dihydro-10-hydroxyavermectin B2a/B2b, which were characterized : by their NMR and mass spectra.
1o EXAMPLE 19.
23,24-Dehydro-10,11-dihydro-10 fluoroavermectin B2a/B2b.
When 5-O tert-butyldimethylsilyl-23,24-dehydro-10,11-dihydro-10-fluoroavermectin B2a/B2b is treated with a solution of anhydrous hydrogen fluoride - pyridine - te~rahydrofuran as fully described in example 5 one obtains 23,24-dehydro-10,11-dihydro~10-fluoroavermectin B2a/B2b which is characterized by its mass spectrum and lH- and 13C-NMR spectra.
5-O-tert-Butyldimethylsilyl-avermectin B2a/B2b aqlYcone.
A ~olution containing 400 mg of avermectin B2a/B2b aglycone (prepared as decribed in Uni~ed States Patent No. 4,206,205) and 544 mg o~ imidazole in 8.0 ml of dimethylformamide was stirred at room temperature until all was in solution. Then 600 mg of tert-butyldimethylsilyl chloride was added in on~
portion and ~he reaction mixture was stirred for an additional 50 minutes at room tempera~ure, when water was added. The rPaction product was isolated by 2~)~j7~;7~
~/DLRll - 37 ~ 17665IA
extraction with ether, washing of the extracts several times with water, then saturated aqueous sodium chloride solution, drying over magnesium sulfate, and concentration to 800 mg of solid residue. Purification by prepara~ive silica gel layer chromatography with 5% tetrahydrofuran in methylene chloride gave 330 mg of 5-O-ter~-butyldi-methylsilyl-avermectin B2a/B2b aglycone, which was characteriz~d by its mass a~d NMR spectra.
S-O-tert-Butyldimethylsilyl-7,13,23-tri-O-trimethYlsilYlavermectin B2a/B2b aql~cone.
A solution of 640 mg of 5-O-tert-butyldimethylsilyl-avermectin B2a/B2b aglycone in 7.5 ml of anhydrous dimethylformamide is stirred at room temperature while 15 ml of bis(trimethylsilyl) trifluoroacetamide is added dropwise. After s~anding an additional 3 hours the reaction mixture is evaporated in high vacuum to a glass, which is characterized by its mass and NMR spectra as 5-O-tert-butyldimethylsilyl-7,13,23-tri-O-trimethyl-sil.ylavermectin B2a/B2b aglycone. The crude product is used for the next step wi~hout further purification.
5-O-tert-Butyldimethylsilyl-7-O-trimethylsilyl-av rmectin B2a/B2b aglycone.
A solution of 354 mg of 5-O-tert-butyl-dimethylsilyl-7,13,23-tri-O-~rimethylsilylavermectin B2a/B2b aglycone in 100 ml of tetrahydrofuran, 15 ml of water, and 8.4 ml of glacial acetic acid is kept at room temperature for 20 hours, when the ~no~7~
2/DLRll - 38 - 17665IA
solution is concentrated in vacuo to a small volume in a water bath of 35C. Water and ethyl acetate are added and the solution made slightly basic with sodium carbonate. The organic phase is separated, dried, and concentrated in vacuo to a light yellow foam, which i~ characterized by its mass and ~MR
spectra as 5-O-tert-butyldimethylsilyl-7-O-trimethylsilylavermectin B2a/B2b aglycone.
5-O-tert-Butyldimethylsilyl-23,24-dehydro-13-deoxy-13-fluoro-7-O-trimethylsilylavermectin B2a/B2b aqlycone.
To a solution of 40 ~L of diethylamino-sulfur trifluoride (DAST) in 1.5 mL of anhydrous methylene chloride stirred at -78C under a blanket of nitrogen, a solut~on of 100 mg of 5-O-tert-butyldi-methylsilyl-7-O-trimethylsilylavermectin B2a/B2b aglycone in 1.5 mL of anhydrous methylene chloride is added dropwise. Subsequently the reaction mixture is kept for 30 minutes at -78C, followed by 6D minutes at -20C, and 90 minutes at room tempPrature. Then dilute aqueous sodium bicarbonate solution is added slowly with ice cooling, and the mixture is extracted with ether, the ether extract is washed with water, dried, and concentrated in vacuo and under high vacuum to a light foam. Purification by preparative silica gel layer chromatography gives 5-O-tert-butyl-dime~hylsilyl-23,24-dehydro-13-deoxy-13-fluoro-7-O-3Q trimethyl~ilylavermectin B2a/B2b aglycone, which ischaracterized by its mass and NMR spectra. This product is obtained as a mixture of ~he ~wo C-13 epimeric 13-alpha- and 13-b~ta fluorocompounds.
37~77 2/DLRll - 39 - 17665IA
23,24-Dehydro-13-deoxy-13-fluoroavermectin B2a/B2b aqlycone. _ _ A solution of 21.6 mg of 5-O-tert-butyldimethylsilyl-23,24 dehydro-l3-deoxy-}3-fluoro-7-O-trimethylsilylavermectin B2a/B2b aglycone in 2.0 mL of an anhydrous hydrogen fluoride - p~ridine-tetrahydrofuran mixture prepared as de~cribed in Example 5 is held at room temperature for 48 hours.
Then the reaction mixture is poured into dilute aqueous sodium bicarbonate sslution and extracted with ethyl acetate, washed with water, dried, and evaporated to a light colored glass. Purification by preparative silica gel layer chromatography gives the two C-13 epimeric 23,24-dehydro-13-deoxy-13-fluoroavermectin B~a/B2b aglycones, which are charac~erized by their mass and NMR spectra.
Claims (13)
1. A compound having the formula:
wherein A represents a single bond or a double bond; R1 is iso-propyl or sec-butyl;
R2 is hydroxy, ketone, loweralkoxy, or protected hydroxy;
R3 is hydrogen, hydroxy, halogen or ketone, however R3 is present only when A represents a single bond;
R4 is hydrogen, hydroxy, halogen,
wherein A represents a single bond or a double bond; R1 is iso-propyl or sec-butyl;
R2 is hydroxy, ketone, loweralkoxy, or protected hydroxy;
R3 is hydrogen, hydroxy, halogen or ketone, however R3 is present only when A represents a single bond;
R4 is hydrogen, hydroxy, halogen,
2/DLR11 - 41 - 17665IA
o r R5 is hydroxy, ketone, -NR6R7 or =NHNCNR6R7;
R6 and R7 are independently hydrogen, loweralkyl, or loweralkanoyl.
and the trisubstituted silyl protected hydroxy derivatives thereof.
2. The compound of Claim 1 wherein A is a single or a double bond;
R1 is isopropyl or sec-butyl;
R2 is hydroxy;
R3 is hydrogen, halogen, hydroxy or oxo;
R4 is hydrogen, hydroxy, halogen, 4'-R5-(.alpha.-olean drosyloxy),4"-R5-[(.alpha.-L-oleandrosyl)-.alpha.-L-(oleandrosyloxy)]; and R5 is hydroxy, amino, loweralkylamino or dilower-alkylamino.
o r R5 is hydroxy, ketone, -NR6R7 or =NHNCNR6R7;
R6 and R7 are independently hydrogen, loweralkyl, or loweralkanoyl.
and the trisubstituted silyl protected hydroxy derivatives thereof.
2. The compound of Claim 1 wherein A is a single or a double bond;
R1 is isopropyl or sec-butyl;
R2 is hydroxy;
R3 is hydrogen, halogen, hydroxy or oxo;
R4 is hydrogen, hydroxy, halogen, 4'-R5-(.alpha.-olean drosyloxy),4"-R5-[(.alpha.-L-oleandrosyl)-.alpha.-L-(oleandrosyloxy)]; and R5 is hydroxy, amino, loweralkylamino or dilower-alkylamino.
3. The compound of Claim 1 where R1, R2 and R3 are as defined in Claim 1 and R4 is halogen.
4. The compound of Claim 3 where R4 is fluorine.
5. The compound of Claim 1 which is 23,24-dehydro avermectin B2a and B2b.
6. The compound of Claim 1 which is 23,24-dehydro avermectin A2a and A2b.
7. The compound of Claim 1 which is 23,24-dehydro-13-deoxy avermectin B2a and B2b aglycone.
8. The compound of Claim 1 which is 23,24-dehydro-10,11-dihydro-10-fluoroavermectin B2a and B2b.
9. The compound of Claim 1 which is 23,24-dehydro-4"-deoxy-4"-methylamino-avermectin B2a and B2b.
10. The compound of Claim 1 which is 4"-oxo-23,24-dehydro avermectin B2a and B2b 4-methyl semicarbazone.
11. The compound o Claim 1 which is 23,24-dehydro-13-deoxy-13-fluoro avermectin B2a and B2b aglycone.
12. A process for the preparation of the compounds of Claim 1 which comprises treating the corresponding protected avermectin A2 or B2 compound with diethyiamino sulfurtrifluoride.
13. A composition useful for treating areas infested with insect pests which comprises an inert carrier and a compound of Claim 1.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US296,172 | 1989-01-13 | ||
| US07/296,172 US4895837A (en) | 1988-01-29 | 1989-01-13 | Avermectin derivatives |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2007677A1 true CA2007677A1 (en) | 1990-07-13 |
Family
ID=23140914
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2007677 Abandoned CA2007677A1 (en) | 1989-01-13 | 1990-01-12 | Avermectin derivatives |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPH02229194A (en) |
| CA (1) | CA2007677A1 (en) |
| IE (1) | IE900143L (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB0302310D0 (en) * | 2003-01-31 | 2003-03-05 | Syngenta Participations Ag | Avermectin- and avermectin monosaccharide derivatives substituted in the 4"- or 4' - positionhaving pesticidal properties |
-
1990
- 1990-01-10 JP JP164490A patent/JPH02229194A/en active Pending
- 1990-01-12 CA CA 2007677 patent/CA2007677A1/en not_active Abandoned
- 1990-01-12 IE IE14390A patent/IE900143L/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02229194A (en) | 1990-09-11 |
| IE900143L (en) | 1990-07-13 |
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