作者:Kazuhiko Tanaka、Hiroe Uno、Hideji Osuga、Hitomi Suzuki
DOI:10.1016/s0957-4166(00)80165-2
日期:1993.4
(1R,2R,6S,7S)-5-Aza-1,10,10-trimethyl-3-oxatricyclo[5.2.1.02,6]decan-4-one (endo-oxazolidinone) and (1R,2S,6R,7S)-isomer (exo-oxazolidinone) are found to be efficient diastereomeric auxiliaries for Diels-Alder reactions, which are promoted by Lewis acid catalysts with predictable absolute stereochemistry. Thus, the reaction of cyclopentadiene with N-crotonyl- or N-cinnamoyl-endo-oxazolidinones gave (1R,2R,3S,4S)-3-methyl- or (1R,2S,3S,4S)-3-phenylbicyclo[2.2.1]hept-5-ene-2-carboxylates, while their enantiomers, i.e. (1S,2S,3R,4R)-3-methyl- or (1S,2R,3R,4R)-3-phenylbicyclo[2.2.1]hept-5-ene-2-carboxylates were obtained stereoselectively from the corresponding exo-oxazolidinone derivatives.
(1R,2R,6S,7S)-5-氮杂-1,10,10-三甲基-3-氧杂三环[5.2.1.02,6]十碳-4-酮(内-氧杂环丁酮)及其(1R,2S,6R,7S)-异构体(外-氧杂环丁酮)被发现是高效的非对映异构Diels-Alder反应辅助剂,这些反应由路易斯酸催化剂促进,并具有可预测的绝对构型。因此,环戊二烯与N-肉桂酰基或N-肉桂酰基-内-氧杂环丁酮的反应生成了(1R,2R,3S,4S)-3-甲基或(1R,2S,3S,4S)-3-苯基双环[2.2.1]庚-5-烯-2-羧酸酯,而它们的对映体,即(1S,2S,3R,4R)-3-甲基或(1S,2R,3R,4R)-3-苯基双环[2.2.1]庚-5-烯-2-羧酸酯,则通过相应的外-氧杂环丁酮衍生物以高立体选择性获得。