Bidirectional Asymmetric Allylboration. A Convenient Asymmetric Synthesis of <i>C</i><sub>2</sub>-Symmetric 3-Methylenepentane-1,5-diols and Rapid Access to <i>C</i><sub>2</sub>-Symmetric Spiroketals
作者:Anthony G. M. Barrett、D. Christopher Braddock、Pieter D. de Koning、Andrew J. P. White、David J. Williams
DOI:10.1021/jo991205x
日期:2000.1.1
single-crystal X-ray study of bis-Mosher ester 6g. Desymmetrization and further functionalization of diol 1a were achieved by treatment of the bis-BOC carbonate 13 with IBr in toluene at -80 degrees C to give cyclic iodocarbonate 14 as a single diastereomer. This methodology is also applicable in natural product synthesis; enantiomerically pure spiroketals 1,7-dioxaspiro[5.5]undecanes 18 and 25, the latter
在布朗的无盐条件下,使用1,3-双(二异樟脑硼基硼基)-2-亚甲基丙烷(R,R)-3和(S,S)-3进行醛的双烯丙基硼化可提供C(2)-对称的3-亚甲基戊烷- 1,5-二醇1对映体过量。通过双-双酯6g的单晶X射线研究证实了产品的绝对立体化学。通过在-80℃下用IBr在甲苯中处理双-BOC碳酸酯13,得到二醇1a的不对称化和进一步官能化,得到环状碘代碳酸酯14,为单一非对映异构体。这种方法也适用于天然产物的合成。对映体纯的螺环酮1,7-二氧杂螺[5.5]十一烷18和25,后者代表海绵体20的AB环系统的简便合成方法,