Synthesis of condensed tannins. Part 3. Chemical shifts for determining the 6- and 8-bonding positions of ‘terminal of’(+)-catechin units
作者:Hans K. L. Hundt、David G. Roux
DOI:10.1039/p19810001227
日期:——
Pairs of 8- and 6-functionalized (Br, OH, OAc, CO2Me, and CH2Me groups) 3′,4′,5,7-tetra-O-methyl-(+)-catechins available through selective bromination and debromination reactions and hence via lithio-analogues, provide diagnostic chemical shifts of their residual 6- and 8-protons. These fall within narrow ranges [δ(CDCl3) 6.07–6.24 and 6.30–6.47 respectively] devoid of overlap, which are useful for
通过选择性溴化可获得成对的8和6-官能化(Br,OH,OAc,CO 2 Me和CH 2 Me基)3',4',5,7-四-O-甲基-(+)-儿茶素脱溴反应,并因此通过硫代类似物,提供了其残留的6和8质子的诊断化学位移。它们落在狭窄的范围内[δ(CDCl 3)分别为6.07-6.24和6.30-6.47],没有重叠,这对于区分4,6-和4,8-连接的双黄酮类化合物是有用的。还提供补充的1个H位移参数。