Brominations of Cyclic Acetals from ?-Amino Acids and ?- or ?-Hydroxy Acids withN-Bromosucinimide
作者:J�rg Zimmermann、Dieter Seebach
DOI:10.1002/hlca.19870700423
日期:1987.7.8
or 2-amino-carboxylic acids are treated with N-bromosuccinimide under typical radical-chain reaction conditions (azoisobuytyronitril/CCl4/reflux). Products of bromination in the α-position of the carbonyl group of the five-membered-ring acetals are isolated or identified (2, 5, and 8; Scheme 1). The dioxanones are converted to 2H, 4H-dioxinones under these conditions (12, 14, 15, 21, and 22; Schemes
描述了用于合成对映体纯化合物(EPC)的新型亲电子构件的制备。因此,2-(叔丁基)dioxolanones,-oxazolidinones,-imidazolidinones,并通过-dioxanones新戊醛的缩醛与2-羟基,3-羟基,或2-氨基-羧酸获得与处理Ñ溴代琥珀酰亚胺在典型的自由基链反应条件下(azoisobuytyronitril / CCl 4 /回流)。分离或鉴定了五元环缩醛的羰基的α位上的溴化产物(2、5和8;方案1)。将二恶烷转化为2 H,4 H在这些条件下-dioxinones(12,14,15,21,和22 ;方案2和3)。产物可以转化为丙酮酸的手性衍生物(亚甲基衍生物3和6)或3-氧代丁酸和-戊酸的手性衍生物(16和23)。溴化的机理得到了解释。还讨论了丝氨酸向定电纯的二恶烷酮26–28的转化(方案4)。