Efficient asymmetric synthesis of the vasopeptidase inhibitor BMS-189921

[reaction: see text] An efficient asymmetric synthesis of the vasopeptidase inhibitor BMS-189921 was accomplished. Two short enantioselective syntheses of the common key intermediate (S)-alpha-aminoazepinone 6b were developed. Olefin 3 was converted to 6b via asymmetric hydrogenation. Alternatively, enyne 12 was converted to racemic alpha-aminoazepinone 15b, which was transformed to 6b by a practical dynamic resolution.     

Synthesis and absolute configuration of (+)-2,3,3-trimethyl-2-hydroxybutanoic acid

The absolute configuration of (+)-2,3,3-trimethyl-2-hydroxybutanoic acid, a key intermediate in the synthesis of the HIV-protease inhibitor 1a (isomer A), has been confirmed as (R) on the basis of X-ray analysis.     

A Remarkable Synthesis of the Bicyclo[4.2.1]Nonenedione System

Allylation of the C-2 enolate of the bicyclo[3.3.1]nonenedione 1 proceeds with an unusual acyl migration to yield the C-allyl ester 5 of the rearranged bicyclo[4.2.1]nonenedione system.     

SAR and pH stability of cyano-substituted epothilones

[formula: see text] 3-Cyano epothilones 15-18 are the only examples of non-hydroxy C-3-substituted analogues. Their tubulin binding affinity and cytotoxicity provide meaningful structure-activity relationship information on the dependence of C-1/C-3 conformation upon activity. 12-Cyano epothilone 24 has improved pH stability over epothilone B, and its activity further supports the hypothesis that C-12 stereochemistry is not critical for tubulin affinity.     

苯二酚异构体的电动毛细管色谱-玻碳微电极柱上安培检测分析方法研究

在玻碳纤维微电极上研究了电解液中β－环糊精（ＣＤ）的浓度对邻、间、对苯二酚的循环伏安特性的影响,从实验结果和分子结构水平方面考察了β－ＣＤ与邻、间、对苯二酚的包结作用。研究结果表明,β－ＣＤ与邻、间、对苯二酚的包结作用强弱顺序为间苯二酚、邻苯二酚、对苯二酚。讨论了电泳缓冲液中ΝΗ４Ｃｌ,ＳＤＳ,β－ＣＤ的浓度及ｐＨ值对邻、间、对苯二酚迁移时间的影响。建立了苯二酚异构体胶束电动毛细管色谱－玻碳微电极柱上安培检测分析方法,方法的回收率在９８％～１０３％之间。     

Mass spectra of aminoacyl adenylate pentacoordinated phosphorus compounds

Aminoacyl adenylate pentacoordinated phosphorus compounds were analyzed by field desorption (FD) and fast atom bombardment (FAB) mass spectrometries, together with the B/E linked scan technique, and their mass spectral fragmentation pathways were investigated. For the five bonds (one P-N bond, three P-O bonds and one mixed anhydride bond P-O-CO), the cleavage usually occurred more on the P-N bond, the mixed anhydride bond and the O-C bond adjacent to the P-O bond, and less on the P-O bond. Ion YH(+), corresponding to water loss from protonated 2',3'-O-isopropylidene-adenosine, was the base peak. The results reflect the structural characteristics of aminoacyl adenylate pentacoordinated phosphorus compounds. Copyright 1999 John Wiley & Sons, Ltd.