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Possible Intervention of Prototropic and Silatropic Ene‐type Mechanisms in Asymmetric Catalytic Mukaiyama Aldol Reactions
Author(s) -
Honda Kazuya,
Mikami Koichi
Publication year - 2014
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.201300226
Subject(s) - chemistry , aldol reaction , ene reaction , catalysis , enantioselective synthesis , silane , transition state , medicinal chemistry , stereochemistry , organic chemistry
Prototropic and silatropic ene mechanisms were analyzed in the BINOL‐Ti IV , bisoxazoline (box)‐Cu II , and BINAP‐Pd II complex‐catalyzed asymmetric Mukaiyama aldol reaction of methyl glyoxylate and acetone‐derived 2‐trimethylsiloxypropene. Our ab initio calculations indicate that the BINOL‐Ti IV ‐catalyzed Mukaiyama aldol reaction proceeds through the concerted prototropic or silatropic ene pathways and that box‐Cu II ‐ and BINAP‐Pd II ‐catalyzed reactions proceed through the stepwise prototropic ene pathways. The transition‐state conformations are thus syn ‐clinal with hydrogen and silane as the migratory groups aligned to the formyl oxygen atom in close syn ‐clinal proximity, respectively.