Institute of Organic Chemistry, University of Leipzig , Johannisallee 29, D-04103 Leipzig, Germany.
Org Lett. 2017 Sep 1;19(17):4588-4591. doi: 10.1021/acs.orglett.7b02185. Epub 2017 Aug 15.
The combination of an in situ formed MnL complex (HL = Hacac or R(C═O)CHCOR) and a chiral phosphoric acid HX* allows for a fully catalytic, asymmetric synthesis of 4H-chromenes starting from 2-alkyl-substituted phenols. The aerobic oxidation toward a transient ortho-quinone methide was efficiently catalyzed by a manganese(III) species MnL while the ensuing Michael addition of β-dicarbonyl compounds proved to be catalyzed by a chiral manganese phosphate MnLX*.
原位形成的 MnL 配合物（HL = Hacac 或 R(C═O)CHCOR）与手性磷酸 HX* 的组合允许从 2-烷基取代的苯酚出发，完全催化、不对称合成 4H-色烯。锰（III）物种 MnL 有效地催化了向瞬态邻醌甲叉的有氧氧化，而随后的β-二羰基化合物的迈克尔加成被证明是由手性锰磷酸 MnLX* 催化的。
