Dipolar cycloaddition reaction of diazoalkanes with trimethylsilyl substituted alkynes. Steric control of regiochemistry by the trimethylsilyl group
作者:Albert Padwa、M. Woods Wannamaker
DOI:10.1016/s0040-4020(01)86680-1
日期:1990.1
coefficient with that of the larger dipolarophile LU coefficient. Dipolar cycloaddition of several 2-(trimethylsilyl) substituted alkynes led to the unexpected regioisomer. Regiochemical control can be attributed to steric rather than to stereoelectronic factors when a bulky trimethylsilyl group is attached to the dipolarophile. In certain cases some of the cycloadducts undergo rearrangement to pyrazoles
已经研究了几种三甲基甲硅烷基取代的炔烃与2-重氮丙烷和重氮甲烷的环加成行为。芳基或烷基乙炔基砜反应生成5-磺酰基取代的3H-吡唑,其在光解时挤出氮,以高收率生产环丙烯。区域化学结果与FMO的考虑是一致的,因为首选的加合物是较大的重氮烷烃HO系数与较大的亲二氟体LU系数的并集的结果。几个2-(三甲基甲硅烷基)取代的炔烃的偶极环加成反应导致了意外的区域异构体。当庞大的三甲基甲硅烷基连接到亲极性体上时,区域化学控制可归因于空间而不是立体电子因素。