Synthesis via vinyl sulfones. 27. Total synthesis of cephalotaxine. The first example of an intramolecular [4 + 2] cycloaddition where the dienophile has been delivered from the face opposite to the tethering moiety
Synthesis via vinyl sulfones. 27. Total synthesis of cephalotaxine. The first example of an intramolecular [4 + 2] cycloaddition where the dienophile has been delivered from the face opposite to the tethering moiety
Stereoselectivity in <i>N</i>-Iminium Ion Cyclization: Development of an Efficient Synthesis of (±)-Cephalotaxine
作者:Hao Liu、Jing Yu、Xinyu Li、Rui Yan、Ji-Chang Xiao、Ran Hong
DOI:10.1021/acs.orglett.5b02106
日期:2015.9.18
the concise synthesis of (±)-cephalotaxine. The current strategy features a TiCl4-promoted cyclization and ring-closure metathesis to furnish the spiro-ring system. The stereochemical outcome in the N-acyliminium ion cyclization was rationalized by the stereoelectronic effect of the Z- or E-allylsilane. Two diastereomers arising from the cyclization were merged into the formal synthesis of (±)-cephalotaxine