Relay Catalysis: Manganese(III) Phosphate Catalyzed Asymmetric Addition of ?-Dicarbonyls to ortho-Quinone Methides Generated by Catalytic Aerobic Oxidation.

Title Relay Catalysis: Manganese(III) Phosphate Catalyzed Asymmetric Addition of ?-Dicarbonyls to ortho-Quinone Methides Generated by Catalytic Aerobic Oxidation.
Authors K. Gebauer; F. Reuß; M. Spanka; C. Schneider
Journal Org Lett
DOI 10.1021/acs.orglett.7b02185
Abstract

The combination of an in situ formed MnL3 complex (HL = Hacac or R(C?O)CH2CO2R) 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 MnL3 while the ensuing Michael addition of ?-dicarbonyl compounds proved to be catalyzed by a chiral manganese phosphate MnL2X*.

Citation K. Gebauer; F. Reuß; M. Spanka; C. Schneider.Relay Catalysis: Manganese(III) Phosphate Catalyzed Asymmetric Addition of ?-Dicarbonyls to ortho-Quinone Methides Generated by Catalytic Aerobic Oxidation.. Org Lett. 2017. doi:10.1021/acs.orglett.7b02185

Related Elements

Manganese

See more Manganese products. Manganese (atomic symbol: Mn, atomic number: 25) is a Block D, Group 7, Period 4 element with an atomic weight of 54.938045. Manganese Bohr ModelThe number of electrons in each of Manganese's shells is [2, 8, 13, 2] and its electron configuration is [Ar] 3d5 4s2. The manganese atom has a radius of 127 pm and a Van der Waals radius of 197 pm. Manganese was first discovered by Torbern Olof Bergman in 1770 and first isolated by Johann Gottlieb Gahn in 1774. In its elemental form, manganese has a silvery metallic appearance. Elemental ManganeseIt is a paramagnetic metal that oxidizes easily in addition to being very hard and brittle. Manganese is found as a free element in nature and also in the minerals pyrolusite, braunite, psilomelane, and rhodochrosite. The name Manganese originates from the Latin word mangnes, meaning "magnet."

Phosphorus

Phosphorus Bohr ModelSee more Phosphorus products. Phosphorus (atomic symbol: P, atomic number: 15) is a Block P, Group 15, Period 3 element. The number of electrons in each of Phosphorus's shells is 2, 8, 5 and its electronic configuration is [Ne] 3s2 3p3. The phosphorus atom has a radius of 110.5.pm and its Van der Waals radius is 180.pm. Phosphorus is a highly-reactive non-metallic element (sometimes considered a metalloid) with two primary allotropes, white phosphorus and red phosphorus its black flaky appearance is similar to graphitic carbon. Compound forms of phosphorus include phosphates and phosphides. Phosphorous was first recognized as an element by Hennig Brand in 1669 its name (phosphorus mirabilis, or "bearer of light") was inspired from the brilliant glow emitted by its distillation.

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