Divergent Asymmetric Total Synthesis of (+)-Vincadifformine, (−)-Quebrachamine, (+)-Aspidospermidine, (−)-Aspidospermine, (−)-Pyrifolidine, and Related Natural Products
作者:Nengzhong Wang、Shuo Du、Dong Li、Xuefeng Jiang
DOI:10.1021/acs.orglett.7b01292
日期:2017.6.16
uniformly strategic total synthesis of Aspidosperma alkaloids (+)-vincadifformine, (−)-quebrachamine, (+)-aspidospermidine, (−)-aspidospermine, (−)-pyrifolidine, and nine others from efficiently constructed tricyclic ketone 13 is reported. Highlights of these divergent and practical syntheses include (i) stereoselective intermolecular [4 + 2] cycloaddition to establish a C–E ring with one all-carbon quaternary
Synthesis and Reactions of 2-Arylhydrazinotropones. II. Synthesis of 5-Aryltropolones and B-Ring-Open Colchicine Analogues via Benzidine Type Rearrangement of 2-(2-Arylhydrazino)troponesa
Treatment of a wide variety of 2-(2-arylhydrazino)tropones with ethanolic acid at 50–80°C readily gave the benzidine type rearrangement products, 2-amino-5-(4-aminoaryl)tropones, besides minor amounts of byproducts of various type. The main products were conveniently led to the corresponding 5-aryltropolones. Similarly, 2-(2-arylhydrazino)tropones bearing an isopropyl and isopropenyl group at the 4-position