GB2111501A

GB2111501A - Process for the preparation of 7-methyl-3-methylene-7-octen-1-yl propanoate

Info

Publication number: GB2111501A
Application number: GB08235947A
Authority: GB
Inventors: Csaba Szantay; Lajos Novak; Attila Kis-Tamas; Bela Majoros; Istvan Ujvary; Ferenc Jurak
Original assignee: Egyt Gyogyszervegyeszeti Gyar
Current assignee: Egyt Gyogyszervegyeszeti Gyar
Priority date: 1981-12-18
Filing date: 1982-12-17
Publication date: 1983-07-06
Also published as: FR2518535A1; HU186455B; PT75999B; IT8224818A0; PT75999A; ES8405754A1; IT8224818A1; AU9170682A; ES518341A0; IT1155431B; JPS58110540A

Abstract

7-methyl-3-methylene-7-octen-1-yl propanoate of the formula (I). <IMAGE> is prepared by reacting 3-methyl-3-buten-1-ol (II> <IMAGE> with an alkyl lithium in an aprotic solvent, in the presence of an alkyl amine, under inert gas, at a temperature between -80 DEG C and 0 DEG C, reacting the dianion (III) thus obtained <IMAGE> with a compound (IV> <IMAGE> wherein X stands for a leaving group, preferably a substituted sulfonyloxy group or a halogen atom, at a temperature between -80 DEG C and 0 DEG C, under inert gas, and acylating the 7-methyl-3-methylene-7-octen-1-ol (V) thus obtained <IMAGE> with propanoic acid or with a reactive derivative thereof in an aprotic solvent. The 7-methyl-3-methylene-7- octen-1-yl propanoate produces a strong stimulating reaction on male San Jose scale and can be used in plant protection.

Description

SPECIFICATION Process for the preparation of 7-methyl-3-methylene-7-octen-1 -yl propanoate The invention relates to a new process for the preparation of 7-methyl-3-methylene-7-octen-1 -yl propanoate.

It is known that the 7-methyl-3-methylene-7-octen-1 -yl propanoate of the formula (I)

produces a significantly strong stimulating reaction on male San Jose scale (Quadraspidiotus perniciosus, Comstock).

The San Jose scale is a serious worldwide pest that attacks all part of host trees including the fruit. Rice and Jones demonstrated the existence of a sex pheromone produced by the female San Jose scale which attracted males [R. E. Rice: J. Econ. Ent. 67, (1974); R. E. Rice and R. A. Jones: Can.

Ent. 109, 1403 (1977)]. They also showed that traps baited with virgin females could be used successfully to monitor the multiple male flights. The components of sex pheromone were isolated by Roelofs and al. [M. J. Gieselmann, R. E. Rice and R. A. Jones: J. Chem. Ecol. 5, (1979)]. Two components, present in approximately equal amounts, were identified as (Z)-3,7-dimethyl-2,7octadien-1-yl propanoate and 7-methyi-3-methylene-7-octen-1-yl propanoate. Greenhouse bioassay and field tests have shown that the compounds are independently attractive to male San Jose scale.

The 7-methyl-3-methylene-7-octen-1-yl propanoate has been synthetized by Henrick et al. [R. J.

Anderson, H. R. Chinn, K. Gill and C. A. Henrich: J. Chem. Ecol. 5, 919 (1979)]. The reaction of 2methyl-2-propen-1 -ol with triethyl orthoacetate in the presence of propanoic acid gave via the orthoester Claisen rearrangement ethyl 4-methyl-4-pentanoate, which was reduced with lithium aluminium hydride in dry tetrahydrofurane into 4-methyl-4-penten-1 -ol. This compound was reacted with the bromo compound of triphenylphosphine in the mixture of pyridine and acetonitrile, the 5bromo-2-methyl-1-pentene thus obtained was converted with magnesium, in dry ether into 4-methyl4-pentenylmagnesium bromide, which was reacted with cuprous bromide-dimethyl sulfide complex to give a complex of the di-(4-methyl-4-pentenyl) cuprous bromide formed with dimethyl sulfoxide.The cuprous compound was reacted with 4-pentyn-1-ol propanoate to obtain the 7-methyl-3-methylene 7-octen-1 -yl propanoate.

In a variant of the above synthesis the di-(4-methyl-4-pentenyl) cuprous bromide-dimethyl sulfoxide complex was reacted with the trimethylsilyl ether of 3-butyn-1 -ol to obtain 7-methyl-3methylene-7-octen-1 -ol, which was esterified with propanoic anhydride in pyridine to give the 7 methyl-3-methylene-7-octen-1 -yl propanoate.

The above synthesis is unfavourable and uneconomic because of the expensive reactants (lithium aluminium hydride, triphenylphosphine, dimethyl sulfoxide-cuprous bromide) and the cumbersome reaction steps.

The aim of the present invention was to provide a more economic process for the preparation of the compound of formula (I), which can be more readiiy carried out also on an industrial scale.

According to the invention the 7-methyl-3-methylene-7-octen-1-yl propanoate can be prepared by a new process characterized by a.) reacting 3-methyl-3-buten-1-ol of the formula (II)

with an alkyl lithium in an aprotic solvent, in the presence of an alkyl amine, under inert gas, at a temperature between --800C and OOC, reacting the dianion of the formula (III) thus obtained

with a compound of the general formula (IV)

wherein X stands for a leaving group, preferably a substituted sulfonyloxy group or a halogen atom, at a temperature between -800C and OOC, under inert gas, and acylating the 7-methyl-3-methylene-7octen-1-ol of the formula (V) thus obtained

with propanoic acid or with a reactive derivative thereof in an aprotic solvent; or b.) reacting a dianion of the formula (III) with a compound of the general formula (IV), wherein X is as defined above, at a temperature between -800C and OOC, under inert gas, and acylating the 7methyl-3-methylene-7-octen-1 -ol of the formula (V) thus obtained with propanoic acid or with a reactive derivative thereof in an aprotic solvent, and isolating the compound of the formula (I) thus obtained from the reaction mixture.

The starting substance of the synthesis is the easily available 3-methyl-3-buten-1 -ol of the formula (II), which can be produced by reacting isobutylene with formaldehyde. It is used both for the preparation of the dianion of the formula (Ill) and for the production of the compounds of the general formula (iV). The latter compounds are prepared by converting the hydroxyl group of the 3-methyl-3buten-1 -ol of the formula (II) into a leaving group, preferably a substituted sulfonyloxy group or a halogen atom.The reaction is preferably accomplished with a compound of the general formula (IV), wherein X represents p-toluenesulfonyloxy, p-bromophenylsulfonyloxy, phenylsulfonyloxy, methanesulfonyloxy or halogen, particularly chlorine or bromine. The preparation of these derivatives is performed by known methods, e.g. for the preparation of compounds of the general formula (IV), wherein X stands for alkyl- or arylsulfonyloxy, 3-methyl-3-buten-1 -ol is reacted with the corresponding alkyl- or arylsulfonyl halide in the presence of a basic acid binding agent (e.g. triethylamine, pyridine), preferably in an aprotic solvent (benzene, ether, dichloromethane, etc.) between -200C and +300 C.

The compounds of the general formula (IV), wherein X is a halogen atom, can be produced easily by reacting compounds of the general formula (IV), wherein X represents an alkyl- or arylsulfonyloxy group, with an alkali halide, preferably lithium bromide or sodium iodide, in an aprotic polar solvent (e.g. acetone, dimethylformamide, etc.).

For the preparation of the dianion of the formula (ill) 3-methyl-3-buten-1-ol is reacted with an alkyl lithium, preferably butyl lithium, in the presence of an alkyl amine, preferably N,N,N,Ntetramethylethylenediamine. The reaction is performed in an aprotic solvent, preferably in an ethertype solvent (e.g. diethyl ether), under cooling, at a temperature between -800C and OOC. As the dianion of the formula (Ill) decomposes on the effect of oxygen, the reaction is carried out under inert gas, preferably under nitrogen or argon. The inert gas atmosphere is maintained until the reaction is complete. The 7-methyl-3-methylene-7-octen-1-ol of the formula (V) thus obtained can be isolated from the reaction mixture by methods known per se.For the acylation thereof preferably propanoic halides or anhydride, particularly propanoic chloride can be used. When carrying out the acylation with propanoic acid, a dehydrating agent (e.g. dicyclohexylcarbodiimine) is also added to the reaction mixture. The reaction is performed in an aprotic solvent (e.g. in ether or tetrahydrofurane). The compound of the formula (I) thus obtained can be isolated from the reaction mixture by methods known per se (e.g. distillation in vacuo).

The invention is illustrated by the following Examples of non-limiting character: Example 1 Preparation of 7-methyl-3-methylene-7-octen-l -yl propanoate a.) Preparation of 1-tosyloxy-3-butene [(IV), X=tosyloxy] A solution of 4.3 g (0.05 moles) of 3-methyl-3-buten-1-oi and 5.4 ml (0.075 moles) of anhydrous pyridine in 10 ml of anhydrous ether is cooled to -1 00C,and 4.5 g (0.05 moles) of p-toluenesulfonic chloride are added. The reaction mixture is stirred at OOC for one hour and poured onto ice. The aqueous suspension is extracted three times with a total amount of 1 50 ml of ether, the ethereal extract is dried and the solvent is distilled off.The residual oil is purified by column chromatography (Kieselgel G; heptaneethyl acetate 4:1), but, if desired, this step can be omitted, the crude product can be used for the further reaction steps without purification.

Yield: 1 5.3 g (85%) Rf (methylene chloride)=0.5 IR (film): 3050, 1645, 1595, 1450, 1355 cm-l.

1H-NMR(CCl4): Us 1.68 (3H, s, CH3), 2.31 (2H, t, J=8 Hz, CH2), 2.42 (3H, s, CH3), 4.1 (2H, t, J=8 Hz, OCH2), 4.7 (2H, m =CH2), 7.48 (4H, m aromatic protons).

Ms: M+ 240 (5), m/e 190 (5), 1 73 (35), 1 55 (20), 91(20), 89 (23), 68 (20), 65 (100), 56 (49), 41(68), 39 (59).

b.) Preparation of 7-methyl-3-methylene-7-octen-1 -ol (V) A solution of 2.32 g (0.02 moles) of tetramethylethylenediamine in 5 ml of anhydrous ether is added to 0.02 moles of butyl lithium (1.2 M hexane solution) under argon, then the mixture is stirred at room temperature for one hour. Then it is cooled to -780C, a solution of 0.86 g (0.01 mole) of 3 methyl-3-buten-1 -ol (II) in 1 ml of anhydrous ether are added, and the mixture is stirred at 0 C for one hour.Then the reaction mixture is cooled again to -780C, a solution of 2.4 g (0.01 mole) of 1tosyloxy-3-methyl-3-butene [(IV): X=tosyloxy] in 3 ml of anhydrous ether is added, the mixture is stirred at 0CC for one hour and allowed to stand overnight at -100C. Then it is diluted with 20 ml of ether at -1 00C, the ethereal solution is acidified with a 1:1 aqueous hydrogen chloride solution (pH=6) and shaken at 0 C subsequently with 10 ml of water and 5 ml of saturated sodium hydrogen carbonate solution. The aqueous phase is shaken twice with a total amount of 100 ml of ether. The ethereal phases are combined, dried over magnesium sulfate and the solvent is distilled off. The residual oil is purified by column chromatography (Kieselgel G, heptane-ethyl acetate 4:1.5).

Yield: 1.0 g (65%) Rf (heptane-ethyl acetate 4:1.5)=0.55 IR (film): 3300,3040,1635,1440, 1365, 1030,870cm1.

1H-NMR(CCl4): S 1.3 (2H, m, CH2), 1.7 (3H, d, J=1 Hz, CH3), 2.0 (4H, t, J=6 Hz, 2CH2), 2.15 (1 H, s, OH), 2.2 (2H, t, J=6 Hz, CH2), 3.6 (2H, t, J=6 Hz, CH2-O), 4.64 (2H, m, =CH2), 4.78 (2H, m, =CH2).

Ms: M+ 154 (1); m/e 136 (10), 123 (5),121 (14), 109 (24), 107 (16), 101 (17), 93 (23), 89 (6), 83 (16), 81(37), 71(8), 69 (69), 68 (100), 67 (54), 55 (43), 53 (32).

c.) Preparation of 7-methyl-3-methylene-7-octen-1 -yl propanoate (I) To a solution of 1.54 g (0.1 mole) of 7-methyl-3-methylene-7-octen-1 -olin 5 ml of anhydrous ether cooled to OOC, 1.2 g (0.015 moles) of anhydrous pyridine and 0.92 g (0.01 mole) of propanoic chloride are added. The reaction mixture is allowed to stand for 5 minutes, then filtered on a short column (Kieselgel G), the column is washed with ether, and the solvent is distilled off in vacuo.

Yield: 1.85 g (88%).

Rf (heptane-ethyl acetate 4:1) =0.8 IR (film): 3040, 1730, 1635, 1450, 1365, 1250, 1160, 1060, 865 cm-1 1H-NMR(CCl4): # 1.1 (3H, t, J=7 Hz, CH3), 1.25 (2H, m, CH2), 1.67 (3H, s, CH3), 2.0 (4H, t, J=6 Hz, 2CH2), 2.3 (4H, m, 2CH2), 4.05 (2H, t, J=8 Hz), 4.58 (2H, m, =CH2), 4.7 (2H, m, =CH2) Ms:M+210 m/e 153(20), 136(41), 121(31), 109(26), 108(30)107 (31),95 (50),93 (42), 81(100), 69(74), 68(45), 57(40), 55(54), 53(23), 41(80), 28(41).

Example 2 Preparation of 7-methyl-3-methylene-7-octen-1-ol (V) To a hexane solution of 1 5.7 ml (0.02 moles) of butyl lithium a solution of 2.32 g (0.02 moles) of tetramethylethylenediamine in 5 ml of anhydrous ether is added at OOC, under nitrogen. The mixture is stirred at room temperature for one hour, then cooled to -78 C, and a solution of 1.69 g (0.01 mole) of 4-bromo-2-methyl-1 -butene in 2 ml of anhydrous ether is added. The mixture is stirred at 0 C for 30 minutes, poured onto ice, acidified with cold, 1:1 aqueous hydrogen chloride solution (pH=6.5), the organic phase is separated, the aqueous phase is extracted with ether, the ethereal phases are combined and washed with saturated sodium chloride solution, dried, the solvent is distilled off and the residual oil is purified by column chromatography.

Yield: 0.9 g (52%), the product was found to be identical to the compound prepared according to Example 1/b.

Claims

1. A process for the preparation of 7-methyi-3-methylene-7-octen-1 -yl propanoate of the formula (1),

characterized by a.) reacting 3-methyl-3-buten-1 -ol of the formula (II)

with an alkyl lithium in an aprotic solvent, in the presence of an alkyl amine, under inert gas, at a temperature between -80 C and OOC, reacting the dianion of the formula (III) thus obtained

with a compound of the general formula (IV)

with propanoic acid or with a reactive derivative thereof in an aprotic solvent; or b.) reacting a dianion of the formula (Ill) with a compound of the general formula (IV), wherein X is as defined above, at a temperature between -800C and OOC, under inert gas, and acylating the 7methyl-3-methylene-7-octen-1 -ol of the formula (V) thus obtained with propanoic acid or with a reactive derivative thereof in an aprotic solvent, and isolating the compound of the formula (I) thus obtained from the reaction mixture.

2. A process according to variant a.) of claim 1, characterized by using butyl lithium as alkyl lithium.

3. A process according to variant a.) of claim 1, characterized by using tetramethylethylenediamine as alkyl amine.

4. A process as claimed in variant a.) of claim 1 or in claim 2 or 3, characterized by carrying out the reaction of 3-methyl-3-buten-1-ol with an alkyl lithium in an ether-type aprotic solvent, preferably in diethyl ether or hexane or in a mixture thereof.

5. A process according to variant a.) or b.) of claim 1, characterized by using an 1 -alkyl- or 1 -aryi- sulfonyl oxy-3-methyl-3-butene as compound of the general formula (IV).

6. A process as claimed in claim 5, characterized by using as compound of the general formula (IV) methyl-, phenyl-, p-bromophenyl- or p-toluene-sulfonloxy-3-methyl-3-butene.

7. A process according to variant a.) or b.) of claim 1, characterized by using a 1-halo-3-methyl-3- butene as compound of the general formula (IV).

8. A process as claimed in variant a.) or b.) of claim 1, characterized by acylating the alcohol of the formula (V) with propanoic chloride or propanoic anhydride.

9. A process according to variant a.) or b.) of claim 1, characterized by carrying out the acylation of the alcohol of the formula (V) with propanoic acid, in the presence of a dehydrating agent.

10. A process as claimed in claim 8 or 9, characterized by carrying out the acylation in an aprotic solvent, preferably in ether or tetrahydrofuran.

11. A process for preparing the compound of the general formula I substantially as hereinbefore described in Example I or Example II.

1 2. 7-methyl-3-methylene-7-octen-1 -yl propanoate made by a process as claimed in any one of claims 1 to 11.