Pandidurai Solai, Sekar Govindasamy
Department of Chemistry, Indian Institute of Technology Madras, Chennai-600036, India.
Org Biomol Chem. 2024 Oct 15;22(40):8119-8124. doi: 10.1039/d4ob01411a.
An efficient method for the asymmetric one-pot synthesis of -phenyl thioether-tethered tetrasubstituted chiral 4,5-dihydropyrrole-3-carbaldehydes have been developed using readily available benzothiazolium salts and α,β-unsaturated aldehydes as starting materials in the presence of the chiral organocatalyst ()-diphenylprolinol trimethylsilyl ether. The protocol afforded various functionally enantioenriched chiral tetrasubstituted 4,5-dihydropyrrole-3-carbaldehydes in high yields, with excellent enantio- and diastereoselectivity (≤90% yield, ≤98% ee, and >20 : 1 d.r.). This asymmetric one-pot reaction starts with the reaction of azomethine ylides with dipolarophiles to yield pyrrolo-thiazine-2-carbaldehydes as intermediates. Subsequently, the electrophile alkyl halide is attacked by the sulfur atom of the intermediate, followed by C-S bond cleavage (ring-opening), which furnishes the desired chiral tetrasubstituted 4,5-dihydropyrroles.
以易得的苯并噻唑鎓盐和α,β-不饱和醛为起始原料，在手性有机催化剂()-二苯基脯氨醇三甲基硅醚存在下，开发了一种高效的一锅法不对称合成苯基硫醚连接的四取代手性4,5-二氢吡咯-3-甲醛的方法。该方法以高产率提供了各种功能化的对映体富集的手性四取代4,5-二氢吡咯-3-甲醛，具有优异的对映选择性和非对映选择性（产率≤90%，对映体过量值≤98%，非对映体比例>20:1）。这种不对称一锅反应始于甲亚胺叶立德与亲偶极体反应生成吡咯并噻嗪-2-甲醛作为中间体。随后，亲电烷基卤化物被中间体的硫原子进攻，接着是C-S键断裂（开环），从而得到所需的手性四取代4,5-二氢吡咯。
