A New Efficient Stereoselective Debromination Reaction with Trialkylgermanium Hydrides Useful in the Design of Short Synthetic Routes to β-Lactamase Inhibitor Prodrugs
作者:Timothy Norris、Christian Dowdeswell、Natalka Johnson、Dan Daia
DOI:10.1021/op050151s
日期:2005.11.1
suitable for prodrug use in high yields. The bromine abstraction usually results in favoured formation of the 6-β-hydroxymethyl epimer relative to the 6-α-hydroxymethyl epimer in ratios that exceed 97:3. Reaction of pure 6-α-hydroxymethyl-6-β-bromo-penicillate-1,1-dioxide ester results in almost exclusive formation of 6-β-hydroxymethylsulbactam ester. This methodology conserves the C−C bond formation at C-6
从β内酰胺酶抑制剂6-β-hydroxymethylsulbactam衍生的前药能够有效地在三个步骤通过使利用三的高度立体选择性的自由基脱溴使用合成Ñ-丁基氢化锗。该试剂能够从高产率的适合于前药使用的差向异构体6-羟基甲基-6-溴青霉酸酯-1,1-二氧化物酯和官能化酯对的C-6位置提取溴。相对于6-α-羟甲基差向异构体,比率超过97∶3,溴的提取通常导致6-β-羟甲基差向异构体的有利形成。纯的6-α-羟甲基-6-β-溴青霉酸酯-1,1-二氧化物酯的反应导致几乎完全形成6-β-羟甲基舒巴坦酯。该方法通过利用甲酰化反应产生的两种差向异构体来保护C-6处的C-C键形成,这在β-羟甲基舒巴坦前药合成中既困难又非立体选择性。