Conjugate addition to 3-(ptolylsulphinyl)chromone: a route to 2-substituted chromones and chiral substituted chroman-4-ones
作者:Suthiweth T. Saengchantara、Timothy W. Wallace
DOI:10.1016/s0040-4020(01)96020-x
日期:1990.1
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
3-(对
甲苯磺酰基)
苯并二
氢吡喃酮3a经历非对映选择性共轭加成的二
甲基二
甲基碳酸锂,产生
2-甲基-3-(对
甲苯磺酰基)
苯并二氢吡喃-4-酮的混合物。将混合物加热至140℃,以定量产率得到
2-甲基色酮。来自(S)-3a的混合产物
脱硫得到具有90%ee的(S)-
2-甲基苯并-4-
酮。在
甲基添加过程中,羰基和
亚砜氧的螯合导致了非对映异构。