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Chiral Dirhodium(II) Carboxamidate‐Catalyzed [2+2]‐Cycloaddition of TMS‐Ketene and Ethyl Glyoxylate
Author(s) -
Forslund Raymond E.,
Cain James,
Colyer John,
Doyle Michael P.
Publication year - 2005
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200404245
Subject(s) - cycloaddition , chemistry , catalysis , glyoxylate cycle , ketene , steric effects , enantiomer , medicinal chemistry , enantioselective synthesis , enantiomeric excess , ligand (biochemistry) , stereochemistry , organic chemistry , receptor , enzyme , biochemistry
The [2+2]‐cycloaddition reaction between ethyl glyoxylate and trimethylsilylketene is reported. Enantiomeric excesses up to 83% have been achieved with the use of only 1.0 mol % of a previously unreported chiral imidazolidinone‐ligated dirhodium(II) carboxamidate catalyst. An extensive survey of chiral catalysts has shown that enantiocontrol for cycloaddition increases as the steric bulk of the ligand is increased. However, enantioselectivity is increased to 99% ee by the addition of 10 mol % of quinine as a co‐catalyst with a chiral dirhodium(II) azetidinone‐ligated catalyst, and there is a significant decrease in reaction time.