An efficient synthesis of chiral isoquinuclidines by Diels–Alder reaction using Lewis acid catalyst
作者:Masafumi Hirama、Yuji Kato、Chigusa Seki、Hiroto Nakano、Mitsuhiro Takeshita、Noriko Oshikiri、Masahiko Iyoda、Haruo Matsuyama
DOI:10.1016/j.tet.2010.07.026
日期:2010.9
The Diels–Alder reaction of 1,2-dihydropyridine derivatives (1-phenoxycarbonyl-1,2-dihydropyridine 1 or 1-methoxycarbonyl-1,2-dihydropyridine 4) with N-acryloyl (1S)-2,10-camphorsultam (1S)-2 or N-acryloyl (1R)-2,10-camphorsultam (1R)-2} in the presence of Lewis acid, such as titanium tetrachloride, zirconium tetrachloride, and hafnium tetrachloride afforded the endo-cycloaddition product, 2-azabicyclo[2
1,2-二氢吡啶衍生物(1-苯氧羰基-1,2-二氢吡啶1或1-甲氧羰基-1,2-二氢吡啶4)与N-丙烯酰基(1 S)-2,10-樟脑嘧啶的Diels-Alder反应( 1个小号) - 2 或ñ -丙烯酰基(1 - [R)-2,10-樟脑磺(1 - [R )- 2 }中的路易斯酸,如四氯化钛,四氯化锆和四氯化铪的存在,得到内型-环产物2-氮杂双环[2.2.2]辛烷衍生物,收率高,具有非对映选择性。的的绝对立体分配内-环产物(1个小号) -图5a从开始ñ -丙烯酰基(1个小号)-2,10-樟脑磺(1个小号) - 2已被确定为(1小号,4 - [R,7小号),反应机理是建议的。