Enantioselective synthesis of the C5–C23 segment of biselyngbyaside
摘要:
Stereo and enantioselective synthesis of C5-C23 fragment of cytotoxic marine natural product biselyngbyaside is achieved using E-selective methyl lithium addition onto enyne, Crimmin's acetate aldol reaction, Sharpless asymmetric epoxidation, and Julia-Kocienski olefination as the key steps. (c) 2012 Elsevier Ltd. All rights reserved.
employed as substrates to explore Lewis base-catalyzed annulation reactions. This leads to the discovery of a phosphine-catalyzed [3+2] annulation of 1 with electron-deficient alkenes for the construction of exocyclic olefinic cyclopentenes in good yields and moderate E:Z ratios undermildconditions. The annulation is believed to proceed in a tandem [3+2] cyclization and double bond migration in which the