Conjugate addition to 3-(ptolylsulphinyl)chromone: A route to 2-substituted chromones and chiral substituted chroman-4-ones

Article abstract of DOI:10.1016/S0040-4020(01)96020-X

3-(p-Tolylsulphinyl)chromone 3a undergoes diastereoselective conjugate addition of lithium dimethylcuprate, producing a mixture of 2-methyl-3-(p-tolylsulphinyl)chroman-4-ones. Heating the mixture to 140°C gives 2-methylchromone in quantitative yield. Desulphurisation of the mixed products from (S)-3a gives (S)-2-methylchroman-4-one with 90% e.e. Chelation of the carbonyl and sulphoxide oxygens during methyl addition accounts for the diastereo selection.