SYNTHESIS AND DIELS-ALDER REACTIONS OF HOMOCHIRAL 2-SULFINYLMALEATES WITH CYCLOPENTADIENE

Article abstract of DOI:10.1016/S0957-4166(00)80020-8

Enantiomerically pure 2-p-tolylsulfinylmaleates 1, 2 and 3 have been readily prepared by Knoevenagel reaction between (S)-menthyl p-toluenesulfinate and glyoxylic acid.Their asymmetric Diels-Alder reactions with cyclopentadiene have been studied under a wide range of uncatalyzed and catalyzed conditions and the stereochemical results have been explained by assuming a steric control approach, in term of S-cis or S-trans favoured conformations.Uncatalyzed Diels-Alder reactions of 1 and some Lewis acid catalyzed Diels-Alder reactions of 2 show high facial and endo selectivities.The facial selectivity of dienophile 2 highly depends on the Lewis acid, whereas reactivity of 1 and 3 is very sensitive to the solvent.These sulfinylmaleates 1, 2 and 3 act as synthetic equivalents of chiral acetylenedicarboxylates in Diels-Alder reactions after basic elimination of the sulfinylic moiety in the resulting adducts.