Asymmetric Cycloaddition of 1,2-Dihydropyridine Derivatives in the Presence of Lewis Acids
作者:Masafumi Hirama、Yuji Kato、Chigusa Seki、Haruo Matsuyama、Noriko Oshikiri、Masahiko Iyoda
DOI:10.1246/cl.2008.924
日期:2008.9.5
Asymmetric cycloaddition of 1-phenoxycarbonyl- (1) or 1-methoxycarbonyl-1,2-dihydropyridine (2) with N-acryloyl-(1S)-2,10-camphorsultam (3) produced chiral isoquinuclidine 4a or 5a in good yields with excellent diastereoselectivity in the presence of a Lewis acid such as titanium tetrachloride, zirconium tetrachloride, or hafnium tetrachloride. The absolute stereochemistry assignment of endo-cycloaddition products 4a and 5a has been established to be 1S, 4R, and 7S.
1-苯氧基羰基(1)或1-甲氧基羰基-1,2-二氢吡啶(2)与N-丙烯酰基-(1S)-2,10-樟脑磺内酰胺(3)的不对称环加成反应在路易斯酸(如四氯化钛、四氯化锆或四氯化铪)存在下,以高收率生成具有优异对映选择性(diastereoselectivity)的手性异奎宁环4a或5a。内型环加成产物4a和5a的绝对立体化学结构被确定为1S、4R和7S。