Diastereoselective Formation of Dithioacetal Oxides from Aliphatic Sulfines under Thermodynamic Control
作者:Florence Corbin、Carole Alayrac、Patrick Metzner
DOI:10.1002/(sici)1099-0690(199911)1999:11<2859::aid-ejoc2859>3.0.co;2-1
日期:1999.11
a thermodynamic equilibrium between the two diastereomers of α-sulfinyl carbanions 3, at which protonation occurs under kinetic control and with retention of configuration with the assistance of the lithium cation. Moreover, the stereochemistry could be totally reversed by converting the lithiated anion intermediate into an aluminium “ate” complex. Thus, (1R*,SS*)-2,2-dimethyl-1-methylsulfanyl-1-m
α-亚磺酰基碳负离子3的质子化是由有机锂化合物选择性硫代加成到脂肪族亚砜2上而产生的,提供了二硫代乙缩醛4(63-94 %的收率)。具有空间受阻的取代基的非对映异构体比例为52:48至100:0。因此,获得作为单一异构体的(1 S *,S S *)-2,2-二甲基-1-甲基硫烷基-1-甲基亚磺酰基丙烷(4ca)。根据α-亚磺酰基碳负离子的两个非对映异构体之间的热力学平衡来合理化立体选择性的起源3,在动力学控制下发生质子化,并借助锂阳离子保持构型。此外,通过将锂化的阴离子中间体转化为铝“酸酯”配合物,可以完全逆转立体化学。因此,通过该方法选择性地获得(1R *,SS *)-2,2-二甲基-1-甲基硫烷基-1-甲基亚磺酰基丙烷(4ca)(dr= 0:100)。