CA2190851C - Palladium catalyzed ring closure of triazolyl tryptamine - Google Patents

Abstract

A new process is described for the synthesis of the triazolyl tryptamine (.alpha.) and related compounds. The process involves a palladium-catalyzed ring closure between a substituted ortho-iodoaniline and a protected 1-alkynol. The process is carried out at high temperature, e.g. 100 ~C, in a dry inert solvent, e.g., DMF and in the presence of a proton acceptor, e.g., Na2CO3 or a trialkylamine. The triazolyl tryptamine, as well as acid addition salts thereof, is a 5 HT1D receptor agonist having anti-migraine properties.

Description

i.
,_.,';2~ X0851 -I-PCTIUS95f05506 TTTLE OF THE INVENTION
PALLADIUM CATALYZED RING CLOSURE OF TRIAZOLYL
TRYPTAMINE
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to the preparation of a class of 5-heterocyclic substituted tryptamines, e.g., 5-(1, 2, 4-triazol-1-yl) to tryptamine, compounds, therapeutically active as anti-migraine agents.
The invention concerns an improved process for producing these 5-heterocyclic substituted tryptamine derivatives which involves a palladium-catalyzed coupling and ring closure.
is 2. Brief Descril?tion of Disclosures in the Art The complex physiological and pathophysiological processes of the neurotransmitter serotonin (5-HT) are becoming increasingly elucidated.l (Superscripted References are listed in the back). In one role, serotonin acts as a vasoconstrictor in the brain and, 20 hereby, displays beneficial properties in migraine therapy. Its potential as a pharmaceutical agent, however, is limited due to its rapid metabolism in vivo. Over the past few years an extensive effort has been devoted to the development of N,N-dialkyltryptamines as 5-HTID
receptor agonists to achieve the desired activity and selectivity for the as treatment of migraine. Sumatriptan is the first of this class of drugs to be approved for this purpose.2 MK-0462 (developed by Merck & Co.), is described in USP 5,298,520 and is also a potent 5-HT1D receptor agonist that is undergoing clinical studies.

R'O 95132197 PCTlUS95/05506 v~'~190851 NH NMe2 2 S02NHMe HO / I I
s \ I N I H
H
Serotonin (5-HT) Sumatriptan io y,~N ~NMe2 \ I NI / ~
is H \
MK-462 (1) Generally, this class of compounds is made by the Fisher indole reaction for the preparation of the N,N-dimethyltryptamine framework. Application of this methodology to the synthesis of MK-20 0462, however, is ineffective and low-yielding due to the instability of the benzyl triazole moiety to the reaction conditions, which generally leads to polymerization of the triazole moiety, producing oligomers.
What is desired in the art is a highly efficient method for the preparation of the N,N-dimethyltryptamine, MK-0462 (1~ which eliminates the 2s desirable tendency of triazole polymerization.
Larock et al., have shown that coupling of an iodoaniline species with an internal acetylene using palladium catalysis gives 2,3-disubstituted indoles in good-to-excellent yields.3 Smith et al., have also demonstrated this for 4-pyrimidinyl and pyridinyl derivatives of indol-3-ao yl_allcyl piperazines as in published EPO 548 831 A1. Two other applications of this methodology have been demonstrated in the syntheses of hetero-condensed pyrroles4a and tryptophans4b. However, all of these methods require triphenylphosphine, as part of the catalyst system, which is an environmental hazard.

W O 95132197 ~ PCTlUS95105506 ~' si': ..

The application of palladium-catalyzed coupling methodology to the specific synthesis of the 5-triazolyl N,N-dimethyltryptamine ring system, has not been reported previously.
s SUMMARY OF TI-IE INVENTION
We have found that MK-462 can be synthesized in high yield by the palladium-catalyzed coupling/ring closure of a 3-iodo-4-aminobenzyltriazole with a suitably protected butynol derivative to the corresponding tryptophol, followed by conversion of the hydroxyethyl to moiety to a dimethylaminoethyl. The advantages of this new process are -that it does not require the use of triphenylphosphine, and also tetrabutylammonium chloride and lithium chloride and it also eliminates the tendency of triazolyl polymerization as experienced in the Fischer Indole Synthesis. In general, the process can be used to prepare 5-is substituted tryptamines where the 5-substituent is triazolyl, triazolyl methyl, imidazolyl, imidazolylinethyl, tetrazolyl, or tetrazolylmethyl.
By this invention there is provided a process comprising the step of contacting a compound of Structure I with a compound of Structure II to form a compound of Structure lII:

wO 95132197 PCT/US95I05506 1 .- r~.;_" . ~~
2?90851 IN!-X~
Rs~ .X2 ORS
N I
(CH2)n (CH2)P
halo + --ii l ll 1 o N-X~
I
Rs~N.X2 I
(CH2)~ FOR
I (CH2)a is 2o said process being carried out in a dry inert organic solvent for Structures I and II, at a temperature in the range of about 70 to 120°C, in the presence of a palladium catalyst, soluble in said solvent, present in an amount of 0.5 to 5 mole percent relative to I, and in the presence of an inorganic or organic amine compound which functions as a proton 2s acceptor, i.e., acid scavenger, and does not chemically react with said catalyst, wherein:
X1 and X2 are independently ring nitrogen or carbon atoms;
halo represents Br or I;
so a is an integer from 0-l; , p is an integer from 1-4; , R3 is H or linear or branched Cl-C4 alkyl; , R 1 is H or a radical which functions as a hydroxy protecting group, which is removable, under mild acid hydrolyses, for example, by R'O 95/32197 PC1YUS95105506 .;2190851 i ~ .'., s_, , ; , -s-contacting with a mixture of HCl/MeOH, e.g. 1:1 2N HC1/MeOH, at 0-30°C;
R2 is a radical which functions as a terminal acetylene carbon protecting group, which is removable by mild acid hydrolysis, for example, by contacting with a mixture of HCI/MeOH, e.g. 1:1 2N HCl/MeOH at 0-30°C.
DESCRIPTION OF THE INVENTION AND PREFERRED
EMBODIMENTS
to The synthesis of MK-462 (~ is illustrated in the following Scheme 1 below.
A key element of the synthesis is the production of the tryptophol precursor 7, which can be prepared by coupling of 3-iodo-4-aminobenzyltriazole ~ with a suitably protected butynol derivative ~.
is / N~ OR' I
20 'N N a ~N + ~BH2~P
b /I / ~
\. NH2 \ I NHz II

R
25 ~' $:R=H;4_:R=I

WO 95132197 PCT/US95/05506 .
r , ? ~' '21'90851 N-H
c d w n m H
1 o N-Z
NMe2 NMe2 a i is H H \
MK-462 (1) aReaction Conditions: a) ICI, CaC03, MeOH-H20; b) 2 mol %
Pd(OAc)2, Na2C03, DMF, 100°C; c) MeOH-HCI; d) i. MsCI, Et3N, 2o THF; ii. 40% HNMe2; e) Benzoic acid, isopropanol, RT.
The synthesis of MK-462 (~ begins with the preparation of the iodoaniline ~. 4-Aminobenzyltriazole ~ is available in 3 steps and >90% overall yield from 4-nitrobenzyl bromide and 4-amino-1,2,4-25 triazole using a modified literature procedures Reaction of _2 with iodine monochloride in the presence of CaC03 in aqueous methanol furnishes the 4-triazolyliodoaniline ,~ in 91 % yield; some over-iodination occurs to provide 1-3% of the diiodoaniline 4. The over-iodination is not difficult to control since it occurs much more slowly.
ao The palladium-catalyzed coupling/ring closure between the ' iodoaniline ~ and the butynol ~ was found to proceed smoothly in surprisingly high yield in the absence of the standard required reagents triphenylphosphine, tetrabutylammonium chloride, and lithium chloride, and in the absence of any triazolyl-induced polymerization.

W O 95!32197 PCT/US95/05506 .
The coupling reaction between the iodoaniline ~ and various derivatives of 3-butyn-I-of was intimately studied in detail (Table I
~ below). In order to prevent coupling at the terminal carbon of the acetylene, it was found that silyl protection was necessary.3 The silyl groups were incorporated by formation of the dianion with BuLi followed by quenching with two equivalents of the silyl chloride. In the case of the TBDMS-protected (tertiary butyl-dimethylsilyl) alkyne, the bis-silylation unexpectedly did not go to completion; rather, a 1:1 mixture of Sri and Sg resulted.It was found that alternative O-protection could be to carried out by selective hydrolysis of the O-silyl group; for example,, was converted to ~ in quantitative yield using dilute HCl in aqueous methanol. The hydroxy group of ~c_ can then be protected with the TBDMS or THP group to afford the alkynes Sf and,5~, respectively, in quantitative yields.
is effect o_f Bu~mol Protection on Yield of Couplinga 2o Entry Acety lenes Yields of Indoles 1 5a R',R2 = SiEt3 (TES) 6a + 6b (80%) 2 5b R~ = H, RZ = SiEt3 6b (74%) 3 5c R' = H, R2 = SiMe3 6c (56%) 4 5d R~ R2 = TBDMS 6d (78%) , 25 5 5e R' = H, R2 = TBDMS 6e (60%) g 5f R' = TBDMS, R2 = TMS 6f (77%) 7 5g R' = THP, R2 = TMS 6g (79%) aConditions: 2 mol% Pd(OAc)2, Na2C03, DMF, 100°C; Ratio of 3/5 =
30 1:1.05-1.2. Me = methyl, Et = ethyl, TBDMS = t-butyldimethylsilyl, TMS = trimethylsilyl, TES = triethylsilyl, THP = tetrahydropyranyl.
The simplest derivative ~ couples with the iodoaniline ,~ to afford the 2-TMS-indole ør in 56% yield.6 The undesired regioisomer ~
(5%) is also formed (See below in Chart 1). Other undesired impurities WO 95!32197 PCTIUS95105506 y, :.~~~19~851 are also formed. The TMS group is believed to be responsible for these byproducts and the low yield. We surprisingly found that the more stable TES and 1'BDMS groups on the alkyne give indoles ~ and ,~A, respectively, in higher yields (Entries 1 and 4). Although the more stable s C-protection gives better results, the bullcy TBDMS butyne couples considerably slower; therefore we found that TES is a particularly useful protecting group in this specific synthesis because it offers a suitable rate of coupling and stability.
t o CHART 1 _ _ N
is CH2 I OH
\ N
H
a° ;3 Desilylation of the combined indoles 6a and ~b in MeOH-HCl affords tryptophol 7g in 70-80% overall yield after work-up and crystallization (Scheme 1). Desilylation of 2-silylated-indoles can also be 2s carried out with other acids such as alkanoic acids, A1C13, methanesulfonic acid and other sulfonic acids. However, we found that the system MeOH-HCl is decidedly more useful and convenient to use particularly from an environmental standpoint. Conversion of 3_ and Sa to 7 is carried out directly without isolation of C. In the crystallization of 7 30 ~e regioisomer 9_ (6%) is removed in the mother liquor.
Conversion of the tryptophol 7 to MK-0462 (1) involves the formation of mesylate from tryptophol 7 followed by the dimethylamine displacement to afford MK-0462 free base R_g in 79% yield. We unexpectedly found that the mesylate is prone to polymerization from intermolecular alkylation by the triazole; therefore, the mesylate is treated w0 95132197 PCT'/US95105506 _.~ ~.1 ~_z, 9085 ~

directly with 40% dimethylamine. The isolated tryptamine is then purified by addition of a solution of benzoic acid to the free base to afford the MK-0462 as a benzoate salt in 95% yield.
This new synthesis of MK-0462 ( 1_) featuring a palladium-s catalyzed coupling of the iodoaniline 3 and the bis-TES-butynol ,5~ to form the indole ring is an efficient process amenable to scale up that despite formation of several impurities, unexpectedly requires no chromatographic purifications as contrasted to the standard Fischer Indole Synthesis.
io REFERENCES AND NOTES
1. Glennon, R. A.; Darmani, N. A.; Martin, B. R. Life Sciences 1991, 48, 2493.
is 2. (a) Feniuk, W.; Humphrey, P. P. A. Drug Dev. Res. 1992, 26, 235; (b) Hopkins, S. J. Drug of Today 1992, 28, 155.
3. Larock, R. C; Yum, E. K. J. Am. Chem. Soc. 1991, 113, 6689.
4. (a) Wensbo, D.; Eriksson, Jeschke, T.; Annby, U.;
2o Gronowitz, S.; Cohen, L. A. Tetrahedron Lett. 1993, 34, 2823. (b) Wensbo, D.; Eriksson, Jeschke, T.; Annby, U.;
Gronowitz, S.; Cohen, L. A. Tetrahedron Lett. 1993, 34, 6471.

5. Astleford, B. A, Goe, G. L; Keay, J. G.; Scriven, E. F. V. J.
2s Org. Chem. 1989, 54, 731-732.

6. (a) Sc was purchased from Farchan Laboratories. (b) Pd(OAc)2 was purchased from Johnson-Matthey.
8. All new compounds were characterized by 1 H NMR, 13C
NMR and elemental analysis. Selective data (1H NMR at $ 0 250 MHz, 13C NMR at 62.5 MHz):
Jndole 6b: 1H NMR (CDCI3) 8 0.90 (m, 15 H), 1.60 (t, J =
5.2 Hz, 1 H), 3.09 (t, J = 7.9 Hz, 2H), 3.85 (dt, J = 7.9, 5.2 Hz, 2H), 5.40 (s, 2H), 7.10 (dd, J = 8.3, 1.4 Hz, 1H), 7.35 (d, J= 8.3 Hz, 1H), 7.60 (d, J= 1.4 Hz, 1H), 7.92 (s, 1H), 7.98 . : ~,v ~ ,;219 0 8 51 -lo-(s, 1H), 8.10 (s, 1H); 13C NMR (MeOH-d4) b 152.1, 144.5, 140.5, 134.0, 130.3, 126.2, 123.0, 122.3, 119.9, 112.7, 64.5, 55.3, 30.9, 7.9, 4.6; Anal. Calcd for C19H27NSOSi: C, 64.18; H, 7.66; N, 15_76. Found: C, 63.81; H, 7.87; N, s 16.15.
Tr~t_ophQl 7: mp 131-132°C; 1H NMR (DMSO-d6) 8 2.81 (t, J = 7.4 Hz, 2H), 3.63 (dt, J = 7.4, 5.3 Hz, 2H), 4.65 (t, J =
5.3 Hz, 1H), 5.43 (s, 2H), 7.00 (dd, J= 8.4, 1.4 Hz, 1H), 7.15 (d, J= 2.0 Hz, 1H), 7.51 (s, 1H), 7.94 (s, 1H), 8.62 (s, io 1H), 10.85 (s, 1H); 13C NMR (DMSO-d6) 8 151.3, 143.6, 135.7, 127.3, 125.8, 123.6, 121.1, 118.3, 111.7, 111.4, 61.5, 53.0, 28.7; Anal. Calcd for C13H1qN4O: C, 64.44; H, 5.82;
N, 23.12. Found: C, 64.38; H, 5.85; N, 23.28.
Tr~ptamine 8: mp 120-121°C; 1H NMR (DMSO-d6) 8 2.34 1s (s, 6H), 2.63 (m, 2H), 2.93 (m, 2H), 5.43 (s, 2H), 7.05 (m, 2H), 7.31 (d, J = 8.3 Hz, 1H), 7.56 (s, IH), 7.97 (s, 1H), 7.99 (s, 1H), 8.49 (s, 1H); 13C NMR (CDCI3) 151.7, 142.8, 136.4, 127.7, 124.5, 123.1, 121.9,.119_1, 113.9, 112.0, 60.2, 54.6, 45.3, 23.5; Anal. Calcd for C15H19N5: C, 66.89; H, 20 7.I1; N, 26.00. Found: C, 66.89; H, 7.20; N, 26.04.
The above described specific synthesis of MK-462 can also be extended to other active analogs containing an imidazole, triazole or tetrazole in the indole 5-position attached through a ring nitrogen atom, 2s trough a methylene group, or attached directly to the 5-position of the indole ring as illustrated in the following flow scheme:

WO 95J32197 PCTlUS95105506 i.
~''.~~1 90851 -u-FLOW SCHEME
N-X~ /N-X~
Ra~ .Xz Ra~N.Xz N I
I (C Hz)n (CHz)n ~ ~ halo NH
NHz z to la I
/N/-Xi Ra~N.X2 ORS
I (CHz) 15 (CHz)n halo 'E' NHz Rz N-X~
,I , Rs~ N.~z I
(CHz)n / (CHz)P OR
N Rz H

w0 95132197 PCT/US95105506 . -~.~190851 1 N-X~
R3 ~ N.~z I
(CHz)n (CHz) FOR
O R
O ~~~R2 H
N-X~
1o Ra~N.Xz I
(CHz)n / (CHz)P OH
N
H
IV
N-X~
Rs~N ~C2 I
(CHz)n / (CHz)PN(C1-C4)2 N
H
V
In the beginning step of the process, Structure Ia is reacted with a halogenating agent to form Structure I at a temperature of about -10 to 10°C in a suitable solvent and in the presence of a suitable proton acceptor.
so The halogenating agent can be, for example, iodine monochloride, N-iodosuccinimide, N-bromosuccinimde, and the like. By the term "halo" as used herein is meant Br or I.
The values for "n" are 0, 1 and the values for "p" are 1, 2, 3 and 4.

WO 95131197 PCTlUS95105506 '~y;;;:~21.90851 The solvent in this step can be MeOH, MeOH-H20, EtOH, THF-H20; CH2Cl2, and the like, and a useful solvent is 95% MeOH-H20.
Useful proton acceptors which can be used include: CaC03, s K2C03, lVa2C03, Li2C03, LiOH, KOH, NaOH, NaHC03, and the like.
When using N-bromosuccinimide or N-iodosuccinimide, a separate proton acceptor is not required.
A useful set of reaction conditions for the halogenating step is MeOH-H20 (95%), as the solvent, a temperature of about 0°C, to whereby the reaction is carried out at atmospheric pressure under an inert atmosphere, e.g., dry N2, in the presence of calcium carbonate.
Structure II, being the protected I-alkynol, is prepared by reacting the starting 1-alkynol IIa; which can be selected from 2-propyn-1-0l (propargyl alcohol), 3-butyn-1-ol, 4-pentyn-I-ol, and S-hexyn-I-ol:
is H = (CH2)P OH ----~ R2 = (CH2)P ORS
Ila II
where p = 1-4 in a suitable inert organic ether solvent, e.g., tetrahydrofuran, dioxane, diethyl ether, 1,2-dimethoxyethane, and the like, under a dry atmosphere, e.g., dry N2, at a temperature of -50°C to -10°C with a slight excess of n-2s butyllithium, being about 2.1 moles per mole of alkynol for a sufficient time, e.g., 2-8 hours to completely generate the dilithium anion of the alkynol. Then the protecting group is attached by adding a precursor, e.g., chlorotrimethylsilane, in also a slight excess of about 2.1 moles per mole of the lithiumdianion of the alkynol and allowed to stir for 1-4 ' 3o hours, to complete the reaction. The reaction is worked up by conventional procedures to yield the diprotected alkynol II.
The R 1 protecting group can be selectively removed by mild acid hydrolysis, e.g., stirring in about 1:1 by volume 2N HCl/MeOH at below 30°C, e.g., 0-30°C, and recovering the product. The resulting alcohol can be selectively protected with another protecting group, R 1 R'O 95132197 PC1'/ITS95f05506 ,.. ,;.~~~_2T 90851 following the above-described protecting procedure to derive II, where R1 and R2 are different protecting groups.
The silylating agents which can be used are generally halogenated trihydrocarbyl silanes, e.g., chloro-triethylsilane.
s The tetrahydropyranyl, THP, protecting group can be applied by using the starting compound dihydropyran as a precursor, in the presence of an acid catalyst e.g., p-CH3PhS020H, to convert the alkynol to the THP ether.
Structure I is then coupled with Structure II to form to Structure III via a palladium-catalyzed reaction in a dry inert organic solvent containing a soluble palladium catalyst and in the presence of a proton acceptor, being an aromatic amine, alkylamine or inorganic base, which is not a catalyst poison, at a temperature of about 70 to 120°C.
In the Structure IB, R3 is H or C1-C4 linear or branched is alkyl, including methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl and t-butyl.
R 1 is H, or a hydroxy protecting group selected from:
the silyl ligand SiRa3, where each Ra is independently selected from linear or branched C1-C4 alkyl (as described above) or phenyl; and 2o tetrahydropyranyl.
Representative examples of SiRa3 radicals include trimethylsilyl, triethylsilyl, tributylsilyl, triphenylsilyl, dimethyl-t-butylsilyl, dimethylphenylsilyl, diphenylmethylsilyl, triisopropylsilyl, and the like.
25 R2 acts as a protecting group for the terminal acetylene carbon and has the same structure SiRa3 as described above, Both R1 and R2 are removable by mild acid hydrolysis, e.g., contacting with about a 1:1 by volume 2N HCl/MeOH solvent mixture at about 0-30°C for 1-24 hours to completely remove the R1, R2 radicals. .
3o The organic solvent useful in this coupling/ring closure step must be one in which Structure I, Structure II and the palladium-catalyst are soluble and compatible and is chemically inert under the reaction conditions.

i , ' ' -ls-Classes of solvents useful in this reaction are N,N-di(CI-Cø)Cl-C2 alkanoamides, Cq-Cg linear ethers, C4-C( cyclic mono or diethers, di C1-Cq. alkoxyethanes, C(-Clp aromatic hydrocarbons, mono or dichlorinated Cl-C4 allcanes, alkylnitriles, and the like, or mixtures s thereof.
Representative solvents include: dimethylformamide, dimethylacetamide, diethylether, dipropyl ether, tetrahydrofuran, dioxane, 1,2-dimethoxyethane, benzene, toluene, o-xylene, m-xylene, p-xylene, acetonitrile, propionitrile and the like, or mixtures thereof.
to The temperature is earned out in the range of 70 to 120°C.
A useful temperature is in the range of about 90-110°C. Generally, the reaction is earned out under dry N2 at atmospheric pressure.
The palladium catalyst useful in the reaction can be selected for example, from the following classes: Pd alkanoates, Pd acetonates, is pd halides, Pd halide complexes, Pd-benzylidene acetone complexes, and the like. Representative examples include: Pd ()I) acetate, Pd (II) acetylacetonate, Pd (O) bis-dibenzylidene acetone, Pd (II) bromide, Pd (II) chloride, Pd (II) iodide, Pd (II) sulfate, Pd (II) trifluoroacetate, Pd (II) CI2(CH3CN)~ and the like. A useful catalyst is palladium acetate.
20 ~e palladium catalyst is used in an amount of about 0.5 to s mole per cent based on the iodoaniline I and a useful range is about 2 to 3 mole percent of soluble palladium catalyst based on the iodoaniline, I.
The proton acceptor useful in this step is a basic compound which can be organic or inorganic and acts as a proton acceptor and is not 2s a "catalyst poison". By the term "catalyst poison" is meant interaction with the catalyst to inhibit its catalytic activity and prevent the coupling/ring closure between Structure I and II from occurring.
Suitable classes of proton acceptors include allcylamines, aromatic amines, heterocyclic amines, Group I alkali metal and Group II
ao alkaline earth carbonates, bicarbonates, phosphates, bisphosphates, and the like.
Representative compounds include lithium carbonate sodium carbonate, potassium carbonate, sodium bicarbonate, potassium WO 95!32197 PCT/US95/05506 .

., bicarbonate, calcium carbonate, triethylamine, diisopropylethylamine, pyridine, N,N-dimethylaniline, 4-dimethylaminopyridine, and the like.
The removal of the protecting groups R I and R2 from III is usually accomplished by mild acid hydrolysis without the separate s isolation of IIL Where the coupling/ring closure is complete, the solvents are generally removed under reduced pressure. A mixture of about 1:1 by volume 2N HCl/MeOH is added to the concentrate of III at room temperature and the mixture allowed to stir at below 30°C, e.g., 0-30°C, for about 2-4 hours to completely remove both R 1 and R2 protecting to groups to obtain IV.
The replacement of hydroxyl in IV with dialkylamine to produce V is generally carried out as a two-step reaction in one reaction vessel.
The alcohol IV can be reacted with mesyl chloride, is (CF3 S02)2 O, and the like, in a dry inert organic solvent, e.g., tetrahydrofuran, dioxane, diethyl ether, 1,2-dimethoxyethane, dichloromethane, and the like, at about -30 to -10°C, under a dry N2 atmosphere, in the presence of a proton acceptor, being a soluble aliphatic or aromatic amine, e.g., triethylamine, pyridine, diethylinethyl-20 a diisopropylethylamine, tributylamine, 4-dimethylaminopyridine, and the like to form the intermediate mesylate, or sulfonate, in situ.
The dialkylamine analog V can then prepared by simply adding the dialkylamine to the mesylate reaction vessel contents, and allowing to stir at room temperature for 1 hour.
2s The obtained Structure V can be isolated as is or reacted with an appropriate pharmaceutically acceptable acid, e.g., HCI, H2SOq., benzoic acid, succinic acid; lactic acid, malefic acid, and the like, to form the corresponding acid addition salt.
Representative examples of Structure V that can be so produced by the process are:

W O 95/32197 PCl'1US95105506 '2-x190851 N,N-Dimethyl-2-[5-(1,2,4-triazol- I -ylmethyl)- I H-indol-3-yl]ethylamine N,N-Dimethyl-2-[5-( 1,3-imidazol-I -ylmethyl}-1 H-indol-3-yl]ethylamine N,N-Dimethyl-2-[5-(5-methyl-I ,2,3,4-triazol-I -ylmethyl)-1 H-indol-3-yl]ethylamine ' N,N-Dimethyl-2-[5-(1,3,4-triazol-I-ylmethyl)-IH-indol-3-yl]ethylamine N,N-Dimethyl-2-[5-( 1,3,4-triazol-1-yl)-1 H-indol-3-yl]ethylamine N,N-Diethyl-2-[5-( 1,2,4-triazol-1-ylmethyl)-1 H-indol-3-yl]ethylamine N,N-Diethyl-2-[5-( 1,3-imidazol-1-ylmethyl)-1 H-indol-3-yl]ethylamine N,N-Diethyl-2-[5-(5-methyl-1,2,3,4-tetrazol-1-ylinethyl)-I H-indol-3-to yl]ethylamine N,N-Diethyl-2-[5-( 1,3,4-triazol-1-ylmethyl)-I H-indol-3-yl]ethylamine N,N-Diethyl-2-[5-( 1,3,4-triazol-I -yl)- I H-indol-3-yl]ethylamine N,N-Dimethyl-[5-( 1,2,4-triazol-I -ylinethyl)-1 H-indol-3-yl]methylamine N,N-Dimethyl-[5-( 1,3-imidazol-1-ylinethyl)-1 H-indol-3-yl]methylamine is N,N-Dimethyl-[5-(5-methyl-1,2,3,4-tetrazol-I-ylmethyl)-1H-indol-3-yl]methylamine N,N-Dimethyl-[5-( 1,3,4-triazol-1-ylmethyl)- I H-indol-3-yl]methylamine N,N-Dimethyl-[5-( 1,3,4-triazol-1-yl)-I H-indol-3-yl]methylamine N,N-Diethyl-3-[5-( 1,2,4-triazol- I -ylinethyl)-1 H-indol-3-yl]propylamine 2o N~N-Dimethyl-3-[5-(1,3-imidazol-I-yl)-IH-indol-3-yl]propylamine N,N-Diethyl-3-[5-(5-methyl-1,2,3,4-tetrazol-1-ylmethyl)- I H-indol-3-yl]propylamine N,N-Dimethyl-3-[5-( 1,3,4-triazo I- I -ylmethyl)-1 H-indol-3-yl]propyl-amore 2s N,N-Diethyl-3-[5-(1,3,4-triazol-1-yl)-1H-indol-3-yl]propylamine N,N=Dimethyl-4-[5-(3-methyl-I ,2,4,5-tetrazol-I -ylmethyl)-1 H-indol-3-yl]butylamine N,N-Dimethyl-4-[5-(2-ethyl-1,3-ethyl-imidazol-1-ylmethyl)-1 H-indol-3-yl]butylamine 3o N,N-Dimethyl-4-[5-(5-ethyl-1,2,3,4-triazol-1-ylmethyl)-IH-indol-3-yl]butylamine N,N-Dimethyl-4-[5-(2-methyl-1,3,4-triazol-1-ylmethyl) 1 H-indol-3-yl]butylamine N,N-Dimethyl-4-[5-(2-ethyl-1,3,4-triazol-I -yl)-1 H-indol-3-yl]butylamine ,.. ,'; 4. i ', Also included are the alcohol analogs of the above amines, including, e.g., _ 2-[5-( 1,2,4-triazol-1-ylmethyl)-1 H-indol-3-yl]ethylalcohol 2-[5-( 1,3-imidazol-1-ylmethyl)-1 H-indol-3-yl]ethylalcohol 2-[5-(5-methyl-1,2,3,4-tetrazol-1-yhnethyl)-1H-indol-3-yl]ethylalcohol 2-[5-( 1,3,4-triazol-1-ylmethyl)-1 H-indol-3-yl]ethylalcohol 2-[5-(1,3,4-triazol-1-yl)-1 H-indol-3-yl]ethylalcohol [5-(1,2,4-triazol-1-ylinethyl)-1H-indol-3-yl]-methylalcohol 3-[5-( 1,3-imidazol-1-ylinethyl)-1 H-indol-3-yl]propylalcohol l0 4_[g_(5-methyl-1,2,3,4-tetrazol-1-ylinethyl)-1H-indol-3-yl]butylalcohol 2-[5-(2-methyl-1,3,4-triazol-1-ylmethyl)-1 H-indol-3-yl]ethylalcohol 2-[5-(5-methyl-1,3,4-triazol-1-yl)-1 H-indol-3-yl]ethylalcohol The following examples are illustrative of the invention as is contemplated by the inventors and should not be construed to limit the scope or spirit of the instant invention.

2o Step 1: preparation of Iodoaniline 3 _ _ Iodine monochloride ~ N
N' FW 162.36 N' CaC03 / I
25 I FW 100.09 NH MeOH ~ NH
2 z FW 174.21 FW 300.10 °:i~'~ ' ~.' '2190851 Mat ri c Amount .MQI 11~
Aniline ~ 30.0 g 0.17 174.21 Iodine monochloride 30.3 g 0_19 162.3 s Calcium carbonate 34.0 g 0.34 100.09 Methanol 240 mL

Ethyl acetate 350 mL
To a mixture of powdered calcium carbonate (34 g, 0.34 to mol) and aniline ~ (30.0 g, 0.17 mol) in methanol (240 mL) and water (12 mL) at 0°C under nitrogen is added a solution of iodine monochloride (30.3 g, 0.19 mol) in methanol (120 mL) over 0.5 h.
The mixture is warmed to room temperature and quenched with half saturated sodium thiosulphate solution (5 mL). The mixture is is stirred for 30 min. 'The solids are filtered and washed with ethyl acetate (100 mL).
The filtrate is concentrated in vacuo to 100 nlL, diluted with ethyl acetate (250 mL), washed with half saturated sodium thiosulphate (200 mL), dried with magnesium sulfate and concentrated to 100 mL.
2o Hexanes is added to precipitate the iodoaniline 3_ as a pale-tan solid (4$.5 g, 91 %).
Recrystallization of the iodoaniline ~ (24 g.) from ethanol affords the iodoaniline ~ (14.5 g, 60% recovery) as a white powder: mp 114-115°C.
Step 2: Protection of Butvnol as bis-Triethylsilyl-butvnol Sa 1. n-BuLi 2. TESCI
3o H~OH FW 150.7 TES- =~~R2 THF
,5~ R2=TES, FW 298 FW 70.09 ~, RZ-H, FW 184 R'O 95132197 PCTIUS95I05506 ;', ,~2~1:.~0~851 i1 Math ~ ~ ~W
3-Butyn-I-of 958.5 g 13.68 70.09 n-BuLi (1.6 M in Hexane) 17.1 L 27.36 64.06 s Chlorotriethylsilane 4.218 kg 28.04 150.73 THF 15.9 L

Heptane 20 L

Sodium Carbonate 90 g ~ 0.85 105.99 as 1 % (w/w) aqueous solution to Water 30.4 L
Dry tetrahydrofuran (15.9 L) is charged to a flask fitted with a mechanical stirrer and thermocouple under a nitrogen atmosphere and 3-butyn-1-of (958.5 g, 13.68 rnol) is charged to the flask. The mixture is is cooled to -30°C and n-BuLi (17.1 L, 27.36 mol) is added dropwise over 4 h, keeping the temperature below -20°C.
The mixture is aged at -20°C for I.2 h. Chlorotriethylsilane (4.218 kg, 28.04 mol) is added dropwise over 55-60 min, keeping the reaction temperature below -10°C. The mixture is then allowed to warm 2o to room temperature. The reaction is complete after 1.5 h at approximately 22°C.
The solution is cooled to -10°C and 1 % (w/w) Na2C03 (8.4 L) is added over 25 min at <0°C. Heptane ( 10 L) is added and the layers are partitioned. The aqueous layer is extracted with heptane (10 L). The as combined organic layers are washed with water (22 L) and concentrated to a pale orange-yellow oil to afford product Sa (98.1 % yield, 93.8 wt%
purity).

R'O 95!32197 PCTlUS95105506 ~:t,~;':'~i 9as~~

Step 33: ~'alladium-catalyzed Coupligg to Prepare Try~tonhol 7 s ~ N
N OTES pd(OAc)2 I + I I Na2C03, DMF
TES 100°C . 4~1 io FW 300.10 FW 298 ORd N~
is ~ I I 1. MeOH-HCI
2. Na2C03 SiEt3 --H
~: Rd = H; ~: Rd = SiEt3 H

~.2:~ 90851 i ,,: j:, x,11, aterials _ _ . _ Amount mMol MW
Iodoaniline ,~ 9 g 30 - 300.10 bis-TES-butynol 5~, (40 W%) 24.5 g 31.5 298 s Palladium acetate 134.4 mg 0.6 224.5 Sodium carbonate (powdered) 15.9 g 150.0 105.9 Dimethylformamide 120 mL

Solka-Floc 2 g Isopropyl acetate 365 mL

to Water 100 mL

Methanol 35 mL
2N HCl 30111L
Heptane 70 mL
Saturated Na2C03 24 mL
1 s Darco G-60 0.5 g IPAc/Heptane ( 1:2) 36 mL
To dry dimethylformamide (12 mL) is charged a solution of bis-TES-butynol ~ in heptane (24.5 g, 31.5 mmol, 40% by wt). The 20 texture is concentrated under vacuum to a volume.of 22 mL. To this concentrate is charged dimethylfonnamide (78 mL), iodoaniline 3_ (9 g, 30 mmol), and powdered sodium carbonate (15.9 g, 0.15 mol). The mixture is degassed with vacuum/nitrogen purges.
Palladium acetate (134.4 mg, 0.6 mmol) is added and the 25 mixture is heated at 100°C for 4 h.
The product mixture is cooled to room temperature and filtered through Solka-Floc. The cake is washed with dimethyl-formamide (30 mL). The combined filtrate and wash are distilled at 26 mmHg (bp for DMF: 67°C) to ~25 mL to remove --100 mL of distillate.
so Isopropyl acetate (IPAC) (150 mL) and water (50 mL) are added to the distillation residue. The resultant mixture is filtered through 2 g of Solka-Floc and the cake is washed with isopropyl acetate (15 mL). The combined filtrates are washed with water (50 mL) and concentrated to 50 mL.

W O 95/32197 PC'fIUS95105506 w~ ~ X0851 . The above concentrate is diluted with methanol (35 mL) and 2N HCl (30 mL, 2 eq) is added over 20 min, keeping the reaction temperature below 30°C. The mixture is aged at room temperature for 2 hours or until the reaction is complete.
s Heptane (36 mL) is added and the heptane-isopropyl acetate layer is separated. The methanol-water layer containing the product Z is concentrated irc vacuo to 65 mL with the removal of methanol (20 mL).
Isopropyl acetate (50 mL) is added to the mixture. The mixture is cooled to 18°C followed by the addition of saturated aqueous to sodium carbonate (24 mL) over 10 min. Isopropyl acetate (50 mL) is added to the mixture. The aqueous layer is separated and extracted with isopropyl acetate (100 mL). The combined organic solution (200 mL) is treated with Darco G-60 (0.5 g). The mixture is stirred for 5 h and filtered. The filtrate is concentrated to 100 mL to give a thin slurry, is followed by the addition of heptane (34 mL). The slurry is aged at room temperature for 1 h. The solid is filtered and washed with heptane/isopropyl acetate (2:1; 36 mL). The product is dried to afford the tryptophol 7 (5.5 g, 75%). The NMR data and C, H, N analytical data is presented above on "References and Notes".

R'O 95132197 PCT/US95105506 ._ :_<i:~~1~9:0851 SteD 4: MK-0462 Free Base g 1. MsCI, FW 114.55 Et3N, FW 101.19 2. 40% HNMe2 H FW 45.09 Z

N
NMe2 H

MK-462 FreeBase (8) FW 269.35 Materials amount I~1 ~y Tryptophol Z 4.878 0.0201 242.28 Methanesulfonyl chloride 230 g 0.0201 114.55 z5 Triethylamine 264 g 0.0261 101.19 Tetrahydrofuran 97 mL

Aqueous dimethylamine (40%w/w) 49 mL 0.39 45.09 Aqueous potassium carbonate (saturated)15 mL

Isopropyl acetate 100 mL, 3 o Darco G-60 0.48 g Heptane 64 mL

-, W095I32197 PCTIUS95105506 The tryptophol 7 (4.87 g) is slurried in dry tetrahydrofuran (97 mL) and sieve-dried triethylamine (2.64 g, 26.1 mmol) is added. The slurry is cooled to -20°C and methanesulfonyl chloride (2.30 g, 20.1 nunol) is added at <-15°C over 45 min. The reaction mixture is aged for s 30 min, at -20°C.
The slurry is filtered at <-15°C and the filter cake is washed with cold, dry tetrahydrofuran (25 mL).
Aqueous dimethylamine (40% w/w, 49 mL, 0.39 mol) is added to the combined filtrates. The reaction mixture is allowed to i o warm to room temperature.
Most of the THF is removed by distillation under vacuum at <30°C (final volume 60 mL). Isopropyl acetate (50 mL) and saturated aqueous potassium carbonate (5 mL) are added. The layers are well-mixed and separated. The aqueous layer is extracted with isopropyl is acetate (50 mL).
The combined organic layers are washed with saturated aqueous potassium carbonate (10 mL). Isopropyl acetate (20 mL) is added to the diluted organic layer and the product solution is dried by heating under reflux over a Dean/Stark trap. The solution is cooled and 2 o treated with Darco G60 (0.5 g) for 60 min, and the mixture is filtered.
The filtrates are concentrated to 20 mL by distillation under vacuum, seeded and then allowed to crystallize for >1 h. Heptane (64 mL) is added to the seed bed over 1 hour and the slurry is cooled to 0°C.
After a 1 hour age the slurry is filtered. The product is washed with cold 4:1 2s heptane-isopropyl acetate (2 X 10 mL) and dried in a vacuum at 40°C.
The free base of MK-0462 (8) is obtained as a cream-colored solid (4.30 g, 73% yield). The NMR and C,H,N analytical data is presented above on "References and Notes".

;;;w~21v0851 Step 5: Formation of MK-0462 Benzoate _ _ N~ COzH N
~N~N NMe2 / NMe2 s ~ ~ C02H
FW 122.12 /
N
H H
to Free Base ($) Benzoate MK-462 (i) FW 269.35 FW 391.47 Materials - Amount - mMol . MW -is MK-0462 Free base (89 wt% purity) 10 g 33.0 269.35 Benzoic Acid 4.5 g 36.8 122.12 Isopropanol 80 mL
Isopropyl acetate 30 mL, 2o To a solution of MK-0462 free base (10 g, 89 wt% pure) in isopropyl alcohol (80 mL) at room temperature is added a solution of benzoic acid (4.5 g, 36.8 mmol) in isopropyl acetate (20 mL) over 10 min. The mixture is aged at room temperature for 0.5 h, cooled to 0-5°C
and filtered. The cake is washed with isopropyl acetate (10 mL) and 2s dried to give crude MK-0462 benzoate salt (13.1 g, 95 wt% pure, 96%
assay yield). Recrystallized from EtOIi to yield pure solid material. The elemental analysis and analytical spectra were consistent with the proposed structure.

Claims (24)

WHAT IS CLAIMED IS:

1. A process comprising the step of contacting a compound of Structure I with a compound of Structure II to form a compound of Structure III:
said process being carried out in an organic solvent at a temperature in the range of about 70 to 120°C, in the presence of a soluble palladium catalyst, and in the presence of an inorganic or organic amine compound which functions as a proton acceptor and does not chemically react with said catalyst, wherein:
X1 and X2 are independently ring nitrogen or carbon atoms;
halo represents Br or I;
n is an integer from 0-1;
p is an integer from 1 -4;
R3 is H or linear or branched C1-C4 alkyl;

R1 is H or a radical which functions as a hydroxy protecting group, and R2 is a radical which functions as a terminal acetylene carbon protecting group.

2. The process of Claim 1, wherein only one of X1, X2 is a ring nitrogen.

3. The process of Claim 1, wherein halo is I.

4. The process of Claim 1, wherein n is 1 and p is 2.

5. The process of Claim 1, wherein R1 is selected from the group consisting o~ H and a silyl ligand SiR a3, where each R a is independently selected from linear or branched C1-C4 alkyl, phenyl and tetrahydropyranyl;
and R2 is selected from SiR a3, where R a is defined herein.

6. The process of Claim 5, wherein said SiR a3 radical is selected from trimethylsilyl, triethylsilyl, tributylsilyl, triphenylsilyl, dimethyl-t-butylsilyl, dimethylphenylsilyl, diphenylmethylsilyl and triisopropylsilyl.

7. The process of Claim 1, wherein said solvent is selected from N,N-di(C1-C4) C1-C2 alkanoamides, C4-C8 linear ethers, C4-C6 cyclic mono or diethers, di C1-C4 alkoxy ethanes, C1-C10 aromatic hydrocarbons, mono-chlorinated C1-C4 alkanes, di-chlorinated C1-C4 alkanes and alkyl nitriles.

8. The process of Claim 7, wherein said solvent is dimethylformamide (DMF).

9. The process of Claim 1, wherein said temperature is in the range of about 90 to 110°C.

10. The process of Claim 1 wherein said palladium-catalyst is a palladium alkanoate, palladium halide, palladium acetonate, palladium halide complex or palladium benzylidene acetone complex.

11. The process of Claim 10 wherein said palladium-catalyst is palladium acetate.

12. The process of Claim 1 wherein said palladium-catalyst is present in an amount of 0.5 to 5 mole percent relative to the Structure I.

13. The process of Claim 1 wherein said proton acceptor is selected from Group I alkali and Group II alkaline earth metal carbonates, bicarbonates, phosphates, bisphosphates, C 1-C4.
trialkylamines, aromatic amines and heterocyclic amines.

14. The process of Claim 13 wherein said proton acceptor is sodium carbonate.

15. The process of Claim 1 carried out in the absence of triphenylphosphine.

16. The process of Claim 1 further comprising the step of:
contacting a compound of Structure Ia with a halogenating agent to form Structure I.

17. The process of Claim 16 further comprising the step of treating a compound of Structure III with mild acid hydrolysis to form a compound of Structure IV:

18. The process of Claim 17 further comprising the step of contacting a compound of Structure IV first with an alkylsulfonyl chloride, then with a di C1-C4 alkylamine to form a compound of Structure V:

19. The process of Claim 18 wherein Structure V is N,N-Dimethyl-2-[5-(1,2,4-triazol-1-ylmethyl)-1H-indol-3-yl]ethylamine N,N-Dimethyl-2-[5-(1,3-imidazol-1-ylmethyl)-1H-indol-3-yl]ethylamine N,N-Dimethyl-2-[5-(5-methyl-1,2,3,4-triazol-1-ylmethyl)-1H-indol-3-yl]ethylamine N,N-Dimethyl-2-[5-(1,3,4-triazol-1-ylmethyl)-1H-indol-3-yl]ethylamine N,N-Dimethyl-2-[5-(1,3,4-triazol-1-yl)-1H-indol-3-yl]ethylamine N,N-Diethyl-2-[5-(1,2,4-triazol-1-ylmethyl)-1H-indol-3-yl)ethylamine N,N-Diethyl-2-[5-(1,3-imidazol-1-ylmethyl)-1H-indol-3-yl]ethylamine N,N-Diethyl-2-[5-(5-methyl-1,2,3,4-tetrazol-1-ylmethyl)-1H-indol-3-yl]ethylamine N,N-Diethyl-2-[5-(1,3,4-triazol-1-ylmethyl)-1H-indol-3-yl]ethylamine N,N-Diethyl-2-[5-(1,3,4-triazol-1-yl)-1H-indol-3-yl]ethylamine N,N-Dimethyl-[5-(1,2,4-triazol-1-ylmethyl)-1H-indol-3-yl]methylamine N,N-Dimethyl-[5-(1,3-imidazol-1-ylmethyl)-1H-indol-3-yl]methylamine N,N-Dimethyl-[5-(5-methyl-1,2,3,4-tetrazol-1-ylmethyl)-1H-indol-3-yl)methylamine N,N-Dimethyl-[5-(1,3,4-triazol-1-ylmethyl)-1H-indol-3-yl)methylamine N,N-Dimethyl-[5-(1,3,4-triazol-1-yl)-1H-indol-3-yl)methylamine N,N-Diethyl-3-[5-(1,2,4-triazol-1-ylmethyl)-1H-indol-3-yl]propylamine N,N-Dimethyl-3-[5-(1,3-imidazol-1-yl)-1H-indol-3-yl]propylamine N,N-Diethyl-3-[5-(5-methyl-1,2,3,4-tetrazol-1-ylmethyl)-1H-indol-3-yl]propylamine N,N-Dimethyl-3-[5-(1,3,4-triazol-1-ylmethyl)-1H-indol-3-yl]propyl-amine N,N-Diethyl-3-[5-(1,3,4-triazol-1-yl)-1H-indol-3-yl]propylamine N,N-Dimethyl-4-[5-(3-methyl-1,2,4,5-tetrazol-1-ylmethyl)-1H-indol-3-yl]butylamine N,N-Dimethyl-4-[5-(2-ethyl-1,3-ethyl-imidazol-1-ylmethyl)-1H-indol-3-yl]butylamine N,N-Dimethyl-4-[5-(5-ethyl-1,2,3,4-triazol-1-ylmethyl)-1H-indol-3-yl]butylamine N,N-Dimethyl-4-[5-(2-methyl-1,3,4-triazol-1-ylmethyl)-1H-indol-3-yl]butylamine or N,N-Dimethyl-4-[5-(2-ethyl-1,3,4-triazol-1-yl)-1H-indol-3-yl]butylamine.

20. The process of Claim 19 wherein Structure V is N,N-dimethyl-2-[5-(1,2,4-triazol-1-ylmethyl)-1H-indol-3-yl]ethylamine.

21. The process of Claim 18 wherein:
(a) Compound 2 is contacted with iodine monochloride in 95% MeOH/H2O in the presence of calcium carbonate at 0°C under nitrogen to produce Compound 3;
(b) Compound 3 is contacted with Compound 5a in dry DMF
containing Pd(OAc)2 and sodium carbonate, at about 100°C for a sufficient time to produce Compound 6a;
(c) Compound 6a is contacted with about a 1:1 by volume 2N
HCl/MeOH mixture at 0-30°C for a sufficient time to remove the SiEt3 protecting groups and form Compound 7;
(d) Compound 7 is contacted with mesylchloride in dry tetrahydrofuran at -20°C containing triethylamine under dry nitrogen for a sufficient time to form an intermediate mesylate in situ:
and then contacted with 40% aqueous dimethylamine and the mixture allowed to react for a sufficient time to form Compound 8.

22. A compound of the structure IV:
wherein R3, X1, X2, n and p are as defined in Claim 1.

23. The compound of Claim 22 being:
2-(5-(1,2,4-triazol-1-ylmethyl)-1H-indol-3-yl]ethylalcohol 2-(5-(1,3-imidazol-1-ylmethyl)-1H-indol-3-y1]ethylalcohol 2-(5-(5-methyl-1,2,3,4-tetrazol-1-ylmethyl)-1H-indol-3-yl)ethylalcohol 2-[5-(I,3,4 triazol-1-ylmethyl)-1H-indol-3-yl)ethylalcohol 2-[5-(1,3,4-triazol-1-yl)-1H-indol-3-yl)ethylalcohol [5-(1,2,4-triazol-1-ylmethyl)-1H-indol-3-yl]-methylalcohol 3-[5-(1,3-imidazol-1-ylmethyl)-1H-indol-3-yl]propylalcohol 4-[5-(5-methyl-1,2,3,4-tetrazol-1-ylmethyl)-1H-indol-3-yl]butylalcohol 2-[5-(2-methyl-1,3,4-triazol-1-ylmethyl)-1H-indol-3-yl]ethylalcohol or 2-[5-(5-methyl-1,3,4-triazol-1-yl)-1H-indol-3-yl]ethylalcohol

24. The compound of Claim 23 being 2-[5-(1,2,4-triazol-1-ylmethyl)-1H-indol-3-yl]ethyl alcohol.