N-(2-Nitrophenylsulfonyl)- (o-NBS-AA-OMe, 4) and N-(4-Nitrophenylsulfonyl)-α-amino acid methyl esters (p-NBS-AA-OMe, 5) were N-alkylated with a variety of alkyl halides 6 undersolid-liquid phase-transfer catalysis (SL-PTC) conditions, affording the alkylated products o-NBS-N-R2-AA-OMe 7 and p-NBS-N-R2-AA-OMe 8 in excellent yields without any detectable racemization.
Amino acid derived intramolecular 1,3-dipolar cycloadditions that form bridged medium ring systems with diastereoselective control
作者:Yanbin Liu、Amy Maden、William V Murray
DOI:10.1016/s0040-4020(02)00242-9
日期:2002.4
Intramolecular nitrone cycloadditions using amino acid precursors, generate aminohydroxyazepine and amino hydroxypiperidine templates. The cycloaddition reactions yield either a [4.3.0] fused system or in most cases a [4.2.1] bridged system. The [4.2.1] bridged system allows for the stereospecific preparation of 3-amino-5-hydroxyazepines while the [4.3.0] system allows for the preparation of 3-amino-5-hydroxymethyl