Synthesis of trans- and cis-14-phenylsulfonyl-1,7,9-trioxadispiro[5.1.5.3]hexadecane

Abstract

The synthesis of the trans- and cis-isomers 1a and 1b of 14-phenylsulfonyl-1,7,9-trioxadispiro[5.1.5.3] hexadecane via the addition of an α-sulfonyl carbanion to δ-valerolactone followed by acid-catalysed cyclization is described. Reductive removal of the sulfone group using Raney nickel afforded the parent bis-spiroacetals 9a and 9b together with the spiroacetal alcohol 10 which underwent oxidative cyclization to the parent bis-spiroacetals 9a and 9b upon treatment with iodobenzene diacetate and iodine.