An Intramolecular Prins Double Cyclization Catalyzed by Silyl Triflates<sup>1</sup>
作者:Michael E. Jung、Steve Angelica、Derin C. D'Amico
DOI:10.1021/jo971337v
日期:1997.12.1
Several intramolecular Prins double cyclizations are reported. The 2-alkyl 5-hepten-1,2-diols and their analogues, 9-11, were prepared and oxidized to the aldehydes 6-8 under Swern conditions. Treatment of these alpha-hydroxy aldehydes with TBSOTf and a hindered base gave the products of an intramolecular Prins double cyclization, namely the 7-(silyloxy)-2-oxabicyclo[2.2.1]heptanes, 17-19, in 84-92% yield. These compounds were formed as single diastereomers with only the anti silyl ethers being obtained. The cyclizations occur when five-membered rings are being formed and when the initially formed cation is highly stabilized. Other substrates do not cyclize, e.g., when the alpha-hydroxy aldehydes 20-22, prepared from 26-28, are treated under similar conditions, none of the corresponding cyclization products, 23-25, were obtained.