Serial Radical Cyclization of Branched Carbohydrates. 1. Simple Pyranoside Diquinanes

Article abstract of DOI:10.1021/jo00283a033

The 2-deoxy-3-ketopyranoside 5 is converted efficiently into two multiply branched derivatives containing functionalized alkyl substituents at C2 and geminally at C3.For substrates bearing a 2-iodoethyl group at C2 and, at C3, axial vinyl and equatorial cyanomethyl groups, reaction with tri-n-butyltin hydride causes deiodination and the resulting carbon-centered radical adds serially to the vinyl group and thence to the nitrile.A diquinane fused to the pyranoside ring thereby results.If aldehydo and amido groups are used instead of nitrile, the reaction takes a different course.