Rhodium complexes of (R)-Me-CATPHOS and (R)-(S)-JOSIPHOS: highly enantioselective catalysts for the asymmetric hydrogenation of (E)- and (Z)-β-aryl-β-(enamido)phosphonates

Rhodium complexes of (R)-Me-CATPHOS and (R)-(S)-JOSIPHOS form a complementary pair of catalysts for the highly efficient asymmetric hydrogenation of a selection of (E)- and (Z)-β-aryl-β-(enamido)phosphonates, respectively, in the majority of cases giving excellent yields and ee’s in excess of 99%; the highest to be reported for this class of substrate.

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Dimethyl 2-acetylamino-2-p-tolylethylphosphonateC13H20NO4PEe >99%[α]D = +45.2 (c 1.0, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: unknown

Dimethyl 2-acetylamino-2-phenylethylphosphonateC12H18NO4PEe 99%[α]D = +38.3 (c 1.0, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: unknown

Dimethyl 2-acetylamino-2-p-flourophenylethylphosphonateC12H17FNO4PEe >99%[α]D = +26.4 (c 1.1, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: unknown

Dimethyl 2-acetylamino-2-p-chlorophenylethylphosphonateC12H17ClNO4PEe 99%[α]D = +23.8 (c 1.2, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: unknown

Dimethyl 2-acetylamino-2-p-bromophenylethylphosphonateC12H18NO4PBrEe >99%[α]D = +44.1 (c1.0, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: unknown

Dimethyl 2-acetylamino-2-p-methoxyphenylethylphosphonateC13H20NO5PEe >99%[α]D = +45.4 (c 0.65, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: unknown