A concise and convergent totalsynthesis of the highly cytotoxic marine natural products iejimalide A-D (1-4) is reported, which relies on an effective ring-closingmetathesis (RCM) reaction of a cyclization precursor containing no less than 10 double bonds. Because of the exceptional sensitivity of this polyunsaturated intermediate and its immediate precursors toward acid, base, and even gentle warming
Vinylogous anionic processes in the formation and interconversion of tetracyclic ring systems
作者:Paul D. Thornton、T. Stanley Cameron、D. Jean Burnell
DOI:10.1039/c0ob01152e
日期:——
Tandem oxy-Cope and transannular vinylogous aldol reactions and/or vinylogous retro-aldol, conjugate addition, and transannular vinylogous aldol reactions transformed some tricyclic vinyl enones into fused tetracycles under basic conditions. Mesylates derived from similar tetracyclic products underwent efficient skeletal reorganization via transannular ring-opening but then different modes of transannular
A Sterically-Encumbered, <i>C</i><sub>2</sub>-Symmetric Chiral Acetal for Enhanced Asymmetric Induction in the Pauson−Khand Reaction
作者:Marie E. Krafft、Llorente V. R. Boñaga、Andrew S. Felts、Chitaru Hirosawa、Sean Kerrigan
DOI:10.1021/jo0263667
日期:2003.7.1
High levels of diastereoselection were achieved in the PKR of 1,6- and 1,7-cyclopropylidenynes bearing a bulky propargylic C(2)-symmetric acetal.
高水平的非对映选择性在带有庞大的炔丙基C(2)对称乙缩醛的1,6-和1,7-环丙炔的PKR中实现。
Re-orienting coupling of organocuprates with propargyl electrophiles from S<sub>N</sub>2′ to S<sub>N</sub>2 with stereocontrol
作者:Barry M. Trost、Laurent Debien
DOI:10.1039/c6sc01086e
日期:——
Diorganocuprate(i) reagents derived from lithiated heterocycles and CuCN react with enantioenriched secondary propagryl bromides to give the corresponding propargylated heterocycles.
An efficient and scalable procedure for the synthesis of (S)-cyclopent-2-enol is reported. The two key steps of the synthesis are the Noyori’s Ru-catalyzed transfer hydrogenation of an ynone and ring-closing metathesis of a 1,6-heptadiene.