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Title: New insights into aldol reactions of methyl isocyanoacetate catalyzed by heterogenized homogeneous catalysts

The Hayashi–Ito aldol reaction of methyl isocyanoacetate (MI) and benzaldehydes, a classic homogeneous Au(I)-catalyzed reaction, was studied with heterogenized homogeneous catalysts. Among dendrimer encapsulated nanoparticles (NPs) of Au, Pd, Rh, or Pt loaded in mesoporous supports and the homogeneous analogues, the Au NPs led to the highest yield and highest diastereoselectivity of products in toluene at room temperature. The Au catalyst was stable and was recycled for at least six runs without substantial deactivation. Moreover, larger pore sizes of the support and the use of a hydrophobic solvent led to a high selectivity for the trans diastereomer of the product. The activation energy is sensitive to neither the size of Au NPs nor the support. A linear Hammett plot was obtained with a positive slope, suggesting an increased electron density on the carbonyl carbon atom in the rate-limiting step. As a result, IR studies revealed a strong interaction between MI and the gold catalyst, supporting the proposed mechanism, in which rate-limiting step involves an electrophilic attack of the aldehyde on the enolate formed from the deprotonated MI.
ORCiD logo [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [2] ;  [2] ;  [1] ;  [1] ;  [1]
  1. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Univ. of California, Berkeley, CA (United States)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-05CH11231; DEAC02-05CH11231
Published Article
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 17; Journal Issue: 1; Journal ID: ISSN 1530-6984
American Chemical Society
Research Org:
Univ. of California, Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; aldol reaction; gold catalyst; heterogenized homogeneous catalyst; mechanism; selectivity; support effect
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1339956