Practical radical cyclisations leading to the construction of near-stereopure quaternary carbon stereogenic centres
作者:Raymond McCague、Robin G. Pritchard、Richard J. Stoodley、Douglas S. Williamson
DOI:10.1039/a807930g
日期:——
The 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl auxiliary is effective in directing bromopropargyloxy additions to the olefinic bonds of vinylogous esters/carbonates; in the presence of AIBN and 1-ethylpiperidinium hypophosphite, the adducts undergo highly stereoselective reductive radical cyclisations in which quaternary carbon stereogenic centres are generated.
2,3,4,6-四-O-乙酰基-β-D-吡喃葡糖苷辅助基团在指导溴炔氧加成到乙烯类酯/碳酸酯的烯烃键上非常有效;在AIBN和1-乙基哌啶醇次磷酸盐的存在下,加成产物经历了高度立体选择性的还原自由基环化反应,其中生成了四级碳立体中心。