A Novel Stereoselective Cyclization to Functionalized Dihydropyrans
作者:Ganapathy S. Viswanathan、Jun Yang、Chao-Jun Li
DOI:10.1021/ol990789m
日期:1999.10.1
[GRAPHICS]An indium trichloride-mediated highly diastereoselective tandem carbonyl allylation-Prins cyclization-chlorination of aldehydes with allylstannanegenerated 4-halotetrahydropyrans in high yields, The reaction of 3-trimethylsilylallyltributylstannane with aldehydes led to the formation of 2,6-dialkyl-3,4-dihydropyrans with a cis diastereoselectivity.
Preparation of γ-trimethylsilylallyldibutylstannane grafted on solid support: a clean and easily recyclable reagent for the synthesis of 2,6-disubstituted dihydropyrans
annane grafted on an insoluble macroporous polymer is reported. This bimetallic reagent was treated with aldehydes in the presence of indium trichloride to afford in good yields both symmetrical and unsymmetrical cis-2,6-disubstituted dihydropyrans, practically uncontaminated with organotin residues (less than 20 ppm). The potential for regeneration and reuse of this supported bimetallic reagent is