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 α-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 ...
