BiBr3 initiated cyclization–addition reactions: effect of π-nucleophile on oxocarbenium ion addition and total syntheses of (+)-(S,S)-(cis-6-methyltetrahydropyran-2-yl)acetic acid and its trans-diastereomer
作者:Robert J. Hinkle、Yajing Lian、Nichole D. Litvinas、Alex T. Jenkins、Daniel C. Burnette
DOI:10.1016/j.tet.2005.09.045
日期:2005.12
initiated tandem cyclization–additions of very reactive silyl ketene acetal nucleophiles with δ-silyloxy aldehydes to afford 2,6-disubstituted THP products, diastereoselectivities range from 5–6:1 (trans-/cis-). The selectivity for axial attack on the intermediate oxocarbenium ion is inversely proportional to π-nucleophilicity. We have utilized this chemistry to convert a common starting material to both cis-
对于BiBr 3启动的串联环化反应-将非常活泼的甲硅烷基乙烯酮缩醛亲核试剂与δ-甲硅烷氧基醛加成以提供2,6-二取代的THP产物,非对映选择性为5-6:1(反-/顺-)。轴向攻击中间氧碳鎓离子的选择性与π-亲核性成反比。我们已经利用这种化学方法将一种常见的起始原料转化为首先从Viverra civetta的分泌物中分离出的一种酸的顺式和反式非对映异构体。