Asymmetric Synthesis of 2-Acetyl-4(5)-(1,2,3,4-tetrahydroxybutyl)imidazoles
摘要:
A method for preparing the eight stereoisomers of the biologically active compound (1R,2S,3R)-2-acetyl-4(5)-(1,2,3,4-tetrahydroxybutyl)imidazole (THI, 1) is reported. This method employs a palladium(0)-catalyzed coupling of 1-(ethoxymethyl)-4-iodoimidazole (7) to functionalized vinylstannanes (R)- or (S)-12a,b or 13a,b or 1-alkynylstannanes (R)- or (S)-6a,b to introduce the C-4 imidazole four-carbon side chain. The 1,2-dihydroxy functionality of the butyl side chain was introduced by Sharpless catalytic asymmetric dihydroxylation reactions.
Organometallic reactions. Part XVI. Trihalogenomethyltin compounds: their preparations, properties, and reactions
作者:Alwyn G. Davies、T. N. Mitchell
DOI:10.1039/j39690001896
日期:——
these can then be reduced by trialkyltin hydrides or by lithium aluminium hydride to give the di- and mono-halogenomethyltin compounds, R3Sn·CHX2 and R3Sn·CH2X, respectively. Some properties and reactions of these products have been investigated.
Synthesis of fluorescent and biotinylated analogues of (1R, 2S, 3R)-2-acetyl-4(5)-(1,2,3,4-Tetrahydroxybutyl)imidazole
作者:Alison T Ung、Stephen G Pyne
DOI:10.1016/0040-4039(96)01325-1
日期:1996.8
A method for preparing fluorescent and biotinylated analogues of the biologically active compound (1R, 2S, 3R)-2-acetyl-4(5)-(1,2,3,4-tetrahydroxybutyl)imidazole 1 is reported.
Isotope effects in the base cleavage of (dihalomethyl)trimethyltins. Additional evidence for proposed mechanistic pathways
作者:W. Stanczyk、J. Chojnowski
DOI:10.1016/s0022-328x(00)92673-1
日期:1980.12
Solvent deuterium isotope effects on the reaction rate (RIE) and on the isotopic composition of the product (PIE) were studied for the three component reactions of the base cleavage of (dihalogenomethyl)trimethyltins(Me3SnCHX2; X Cl, Br) in 8/2 v/v n-propanol/water in the presence of ammonia buffer. The results support the mechanisms in which free carbanions are separated in the rate determining
研究了溶剂氘同位素对反应速率(RIE)和产物同位素组成(PIE)的影响,研究了(二卤代甲基)三甲基锡(Me 3 SnCHX 2; XCl,Br)的三价反应在氨水缓冲液中于8/2 v / v正丙醇/水中溶解。结果支持了在涉及溶剂共轭碱,scb的反应的速率确定步骤中分离出游离碳负离子的机理,同时证实了在亲和过程中由氨气催化的亲电助溶剂的重要性(通用基地)。
Catalytic reactions in SnC bond cleavage in basic media
作者:W. Staǹczyk、J. Chojnowski
DOI:10.1016/s0022-328x(00)86073-8
日期:1980.7
involving SnCbondcleavage by solvent conjugate base, the reaction shows catalysis by ammonia acting as a general base as well as base nucleophile catalysis with participation of both ammonia and solvent conjugate base. Comparison of the catalytic constants for these three types of catalysis with those for the Me3SiCHX2 series reveals the enhanced role of general base catalysis in the cleavage of the tin
使用氨缓冲液在正丙醇-水8:2 v / v溶剂系统中研究了(二卤代甲基)三甲基锡(Me 3 SnCHX 2 ; X = Cl,Br)的溶剂分解动力学。除了涉及通过溶剂共轭碱裂解SnC键的简单碱催化外,该反应还显示出氨作为普通碱的催化作用,以及氨和溶剂共轭碱共同参与的碱亲核试剂催化作用。这三种催化类型的催化常数与Me 3 SiCHX 2的催化常数的比较该系列揭示了一般的碱催化作用在锡化合物裂解中的增强作用。锡化合物的两个涉及溶剂共轭碱的反应都比硅类似物的反应慢。