Synthesis of monoamides of methotrexate from L-glutamic acid monoamide t-butyl esters

Abstract

Analogues of methotrexate (amethopterin) (1) with a-or y-monoamide functions [viz. the a-and yprimary amides (16a) and (26a); the following N-substituted amides: a-methyl-, a-ethyl-, a-and ypropyl-, a-isopropyl-, a-butyl-, a-isobutyl-, a-sec-butyl-, a-t-butyl, a-benzyl-, and a-and ycyclohexylamide (1 6b-d), (26d), (1 6e-k), (26k) respectively; and the NN-disubstituted amides: ypiperidide (261) and y-morpholide (26m)l were synthesized starting with t-butyl L-isoglutamine (1 2a), t-butyl L-glutamine (22a), or the appropriate N'-alkyl or N'N'-dialkyl analogues (1 2b-k), (22d), (22k), (221), and (22m). The corresponding N-benzyloxycarbonyl compounds (1 1) and/or (21) from which the above L-glutamic acid derivatives were obtained were generally synthesized by mixedanhydride coupling of Nbenzyloxycarbonyl-L-glutamic acid (9) with the appropriate amine, conversion into the t -butyl ester, and chromatographic separation. The resulting a-monoamide y-t-butyl ester (1 1 ) and y-monoamide a-t-butyl ester (21 ) are unambiguously distinguished by mass spectrometry and 3C n.m.r. spectroscopy. Factors which affect the y-amidelm-amide product ratio are R a RY ~~ t In some cases the separation into X -and y-monoamides could be effected by crystallization prior to ester formation.

Structural comparisons of complexes of methotrexate analogs with Lactobacillus casei dihydrofolate reductase by two dimensional proton NMR at 500 MHz

“…The methotrexate a-monoamide and methotrexate y-monoamide were synthesized as described previously (Antonjuk et al, 1984a). NADP' and NADPH were obtained from Sigma Chemical Co. and used without further purification.…”

“…dihalomethotrexates, prepared by the method of Tomcufcik and Seeger (1961), were gifts from Dr. D. G. Johns and used without further purification. The methotrexate a-monoamide and methotrexate -monoamide were synthesized as described previously (Antonjuk et al, 1984a). NADP+ and NADPH were obtained from Sigma Chemical Co. and used without further purification.…”

Controlled Regioselective Anilide Formation from Aspartic and Glutamic Acid Anhydrides

“…In addition, reactions of primary alkylamines and α-amino acids proceed without regioselectivity. Earlier work has suggested that there is no relationship between the steric and electronic nature of primary amines and the α/γ product distribution from their nucleophilic attack on Cbz-glutamic acid anhydride. The greater regioselectivity of anilines compared to primary alkylamines may be due to their reduced basicity (nucleophilicity) and greater steric bulk.…”

Lipophilic methotrexate conjugates with glucose‐lipoamino acid moieties: Synthesis and in vitro antitumor activity

“…As extensively reported, an increase in the overall lipophilicity of MTX can be achieved by a substitution at one or both the carboxyl groups present in its glutamate moiety [Piper et al, 1982;Antonjuk et al, 1984Antonjuk et al, , 1989Rosowsky et al, 1986;Pignatello et al, 1996Pignatello et al, , 1998Pignatello et al, , 1999Rahman and Cchabra, 1988]. LAA conjugation of anticancer drugs was shown to maintain or even increase the activity against different cell lines in vitro [Wood et al, 1992;Pignatello et al, 1998Pignatello et al, , 2000.…”