Allylation of aldehydes catalyzed by chiral N,N'-bis(N-methyl-2-methylene-4,5-bisphenylimidazole)-1,2-cyclohexane diamine rhodium(III) complexes1

Chiral bis-imidazole rhodium(III) complexes catalyze the allylation of aldehydes by allyltributyltin. The precatalyst was readily prepared from chiral N,N'-bis(N-methyl-2-methylene-4,5-bisphenylimidazole)-1,2-cyclohexanediamine, potassium carbonate, and rhodium(III) chloride trihydrate. The rho...

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Bibliographic Details
Published inCanadian journal of chemistry Vol. 81; no. 11; p. 1206
Main Authors LaRonde, Frank J, Brook, Michael A
Format Journal Article
LanguageEnglish
Published Ottawa Canadian Science Publishing NRC Research Press 01.11.2003
Subjects
Acids
Aldehydes
Catalysts
Chirality
Organometallic compounds
Rhodium
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Summary:Chiral bis-imidazole rhodium(III) complexes catalyze the allylation of aldehydes by allyltributyltin. The precatalyst was readily prepared from chiral N,N'-bis(N-methyl-2-methylene-4,5-bisphenylimidazole)-1,2-cyclohexanediamine, potassium carbonate, and rhodium(III) chloride trihydrate. The rhodium(III) complex produced showed no activity in an allyl transfer process in the presence of the allyltin reagent. However, when silver tetrafluoroborate was added to the pre-catalyst and stirred for 1 h, the resulting system became an efficient catalyst for the allyl transfer process. The reductions produced homo-allyl alcohols with good to excellent yield, although generally with poor facial selectivity (8-10% ee, aryl aldehydes, 4 examples; 99% ee, aliphatic aldehyde, 1 example). [PUBLICATION ABSTRACT] Key words: allylation, aldehydes, enantioselectivity, rhodium(III) tetramine complex.
ISSN:0008-4042
1480-3291