Amnesia-reversal activity of a series of 5-alkoxy-1-arylcarbonyl-2-pyrrolidinones and 5-alkoxy-1-arylmethyl-2-pyrrolidinones
摘要:
A series of 5-alkoxy-1-arylcarbonyl-2-pyrrolidinones (1-27) were prepared by condensation of arylcarbonyl chlorides with 5-alkoxy-2 pyrrolidinones in the presence of butyl lithium in tetrahydrofuran. Alkylation of these intermediates with substituted benzyl bromides or chlorides, under solid/liquid phase-transfer conditions (KOH/Bu4NBr) in tetrahydrofuran, yielded 5-alkoxy-1-arylmethyl-2-pyrrolidinones (28-48). In the first series, the compounds with a 5-n-pentyloxy group had maximal ECS-induced amnesia reversing activity in mice, and in the second series, those with a 5-n-octyloxy group. In both series, substitutions on the phenyl ring had detrimental effects. The two most promising compounds 1-benzoyl-5-n-pentyloxy-2-pyrrolidinone (14) and 1-benzyl-5-n-octyloxy-2-pyrrolidinone (37) were more potent than piracetam and aniracetam and active over broader dose ranges: 50-200 and 50-400 mg/kg, po. Both compounds also reversed scopolamine-induced amnesia in mice, from 50 to 400 mg/kg, po (14) and from 100 to 400 mg/kg, po (37). Finally, 37 showed remarkable activity in protecting the mouse brain against chemically induced hypoxia, with a minimal effective dose of 50 mg/kg, ip, or 100 mg/kg, ip, in NaNO2- or KCN-induced hypoxia.
Allenylmethylsilanes as Nucleophiles in <i>N</i>-Acyliminium Ion Chemistry
作者:Gertjan Mentink、Jan H. van Maarseveen、Henk Hiemstra
DOI:10.1021/ol026615d
日期:2002.10.1
precursors with 2,3-butadienyl(trimethyl)silane and related allenes in the presence of BF(3).OEt(2) provides good yields of N-protected 2-(aminomethyl)-substituted 1,3-dienes, which prove to be useful substrates for subsequent Diels-Alder and alkene metathesis reactions. [reaction: see text]
Applications of Vinylogous Mannich Reactions. Concise Enantiospecific Total Syntheses of (+)-Croomine
作者:Stephen F. Martin、Kenneth J. Barr、Dudley W. Smith、Scott K. Bur
DOI:10.1021/ja990077r
日期:1999.8.1
extraordinarily concise asymmetric syntheses of (+)-croomine (1) have been completed using a novel strategy, highlighted by two vinylogous Mannich reactions as key constructions. The first such reaction involved the addition of 5-(4-bromobut-1-yl)-3-methyl-2-(triisopropylsilyloxy)furan to the N-acyliminium salt derived from the l-pyroglutamic acid derivative 17 to give the adduct [5(S),2‘(S),5‘(S)]-5-(4‘
Silicon-assisted synthesis of bridged azabicyclic systems via N-acyliminium intermediates
作者:Wim J. Klaver、Henk Hiemstra、W.Nico Speckamp
DOI:10.1016/s0040-4020(01)90113-9
日期:1988.1
with five- and six-membered cyclic N-acyliminium ion precursors lead to bridged azabicyclic compounds (Table I). Neat formic acid is the reaction medium of choice in most cases. The cyclization reactions take place with complete regioselectivity. 2-Propynylsilanes are more reactive than allylsilanes. An ordinary olefin reacts poorly. The cyclization products can be useful for the synthesis of γ- and
Influence of N-substituted lactams on acyclic free radical based hydrogen transfer
作者:Yvan Guindon、Mohammed Bencheqroun
DOI:10.1016/s0040-4039(01)01213-8
日期:2001.8
anti Relative stereochemistry is achieved in the hydrogen-transfer reaction of a lactam adjacent to the carbon-centered radical. The sense of diastereoselectivity is reversed using N-substituted lactams, and optimal results favoring syn reduced products are obtained with an alpha -methylbenzyl group and a Boc group. (C) 2001 Elsevier Science Ltd. All rights reserved.