A short multigram asymmetric synthesis of prostanoid scaffolds

Enantiomerically pure polysubstituted cyclopentanes which can be regarded as prostanoid scaffolds have been prepared by an efficient synthetic sequence readily applicable to the preparation of multigram quantities. The first key reaction is the diastereoselective allylmetallation of oxoamide 4 which is readily prepared from γ-butyrolactone and an enantiomerically pure 2,5-dimethylpyrrolidine. The second key-step is an intramolecular [2+2] cycloaddition of a keteneiminium salt leading to bicylo[3.2.0] heptanones. These intermediates have been easily transformed into a variety of prostanoid scaffolds of high enantiomeric purities.     

由炔的金属烯丙化合成二烯烃和环烯烃

炔的金属烯丙化(allylmetallation)是炔的金属烃化反应(carbometallation)的一种,是立体专一地合成多取代烯烃的有效途径。铝烯丙化(allylalumination)和锌烯丙化(allyl-