SYNTHESIS OF NYLSULFONYL-1,7,9-TRIOXADISPIRO[5.1.5.3]HEXADECANE AND NYLSULFONYL-1,7,9-TRIOXADISPIRO[5.1.5.3]HEXADECANE

The synthesis of the trans- and cis-isomers 1a and 1b of ylsulfonyl-1, 7,9-trioxadispiro-[5.1.5.3]hexadecane via the addition of an alpha-sul fonyl carbanion to delta-valerolactone followed by acid-catalysed cycl ization is described. Reductive removal of the sulfone group using Ran ey nickel afforded the parent bis-spiroacetals 9a and 9b together with the spiroacetal alcohol 10 which underwent oxidative cyclization to t he parent bis-spiroacetals 9a and 9b upon treatment with iodobenzene d iacetate and iodine.