Highly diastereoselective cycloaddition reactions of variously substituted 1-thia- and 1-thia-3-aza-buta-1,3-dienes. Synthesis of enantiomerically pure 5,6-dihydro-4H-[1,3]thiazines and 3,4-dihydro-2H-thiopyrans
作者:Anne Harrison-Marchand、Sylvain Collet、André Guingant、Jean-Paul Pradère、Loı̈c Toupet
DOI:10.1016/j.tet.2003.12.041
日期:2004.2
The cycloaddition of 2- or 2,3-substituted 1-thia- and 1-thia-3-aza-4-dimethylamino-buta-1,3-dienes with various dienophiles in the presence of a Lewis acid provides a rapid and diastereoselective access to the 3,4-dihydro-2H-thiopyran and 5,6-dihydro-4H-[1,3]thiazine backbones. The generally observed trans relationship between the two newly created strereogenic centres was demonstrated to be the expression
在路易斯酸的存在下,将2-或2,3-取代的1-硫杂-和1-硫杂-3-氮杂-4-二甲基氨基-buta-1,3-二烯与各种亲二烯物环加成反应提供了快速且非对映的选择性访问3,4-dihydro-2 H -thiopyran和5,6-dihydro-4 H- [1,3]噻嗪骨架。两个新创建的促变构中心之间通常观察到的反式关系被证明是反应热力学控制的表达。使用手性恶唑烷-2-酮衍生的手性亲二烯体使我们能够制备对映体纯的5,6-二氢-4 H- [1,3]噻嗪和3,4-二氢-2 H-硫吡喃。在不对称合成过程中,手性辅助去除步骤最好在甲醇中存在三氟甲磺酸sa的条件下完成。