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Organocatalytic Enantioselective Michael Addition of Pyrazol‐5‐ones to β‐Silylmethylene Malonates: Synthesis of Chiral Organosilanes Under Metal‐ free Conditions
Author(s) -
Chowdhury Raghunath,
Dubey Akhil K.,
Ghosh Sunil K.
Publication year - 2021
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.202100120
Subject(s) - chemistry , enantioselective synthesis , thiourea , squaramide , moiety , catalysis , enantiomer , organic chemistry , combinatorial chemistry , malonate , organocatalysis
Abstract Herein, we report a Michael addition reaction of pyrazolin‐5‐ones with β‐silylmethylene malonates using a squaramide catalyst derived from quinidine under mild reaction conditions. This protocol delivered chiral organosilanes appendage with pyrazole moiety in high yields (up to 90%) and good to excellent enantioselectivities (up to 98 : 2 er). A quinine derived thiourea catalyst deliver corresponding antipode for enantiomers with almost similar level of yields (up to 93%) and good to excellent enantioselectivities (up to 2 : 98 er). The scale‐up reaction for synthesis of two chiral organosilanes confirmed the practical reliability of this protocol.