Palladium[0]-mediated aminospirocyclization of tertiary allylic sulfones. Stereospecific construction of the azabicyclic ring system of cephalotaxine
作者:Zhendong Jin、F.L Puchs
DOI:10.1016/0040-4039(96)01112-4
日期:1996.7
Tertiary allylic sulfones which bear a secondary aminopropyl moiety undergo smooth palladium [0]-mediated spirocyclization. The reaction proceeds via a π-allyl intermediate and the resultant azabicyclic product is formed with net retention of sulfonestereochemistry. The use of tetramethylguanidine as companion base is required for high yielding reactions.
Convergency and Divergency as Strategic Elements in Total Synthesis: The Total Synthesis of (−)-Drupacine and the Formal Total Synthesis of (±)-Cephalotaxine, (−)-Cephalotaxine, and (+)-Cephalotaxine
作者:Qi Liu、Eric M. Ferreira、Brian M. Stoltz
DOI:10.1021/jo0710883
日期:2007.9.1
A conciseroute toward the syntheses of (−)-drupacine and (+)- and (−)-cephalotaxine has been developed. The syntheses rely on Pd(II)-catalyzed aerobic oxidative heterocyclization chemistry, which was employed to rapidly construct an important spirocyclic amine intermediate. A dynamic β-elimination/conjugate addition process was strategically applied to complete the first asymmetric total synthesis