Thiourea catalysis reviews

For reviews on thiourea catalysis, see, Takemoto, Y. (2005) Organic and Biomolecidar Chemistry, 3, 4299-4306. Takemoto, Y. (2006) Yuki Gosei Kagaku Kyokaisfu, 64, 1139-47. Connon, S.J. (2006) Chemistry - A European Journal, 12, 5418-27. 

Abstract After an overview of chiral urea and thiourea synthetic methods, this review describes the main applications of urea and thiourea complexes in asymmetric catalysis. Some recent examples of thioureas as catalysts are also presented. Coordination chemistry of ureas and thioureas is briefly discussed. 

The Mannich reaction and its variants have been reviewed, mainly focussing on asymmetric catalysis thereof. Catalytic, enantioselective, vinylogous Mannich reactions have also been reviewed, covering both direct and silyl dienolate methods. Another review surveys Mannich-type reactions of nitrones, oximes, and hydrazones. A pyrrolidine-thiourea-tertiary amine catalyses asymmetric Mannich reaction of N-Boc-imines (e.g. Ph-Ch=N-Boc) with ethyl-4-chloro-3-oxobutanoate to give highly functionalized product (16). Addition of triethylamine leads to one-pot intramolecular cyclization to give an 0-ethyl tetronic acid derivative (17). ... 

A review has illustrated the importance of atomic-level DFT studies in elucidation of the function of hydrogen bonds in organocatalytic reactions through influence on the mechanism of substrate activation and orientation, and the stabilization of transition states and intermediates. Examples discussed include stereoselective catalysis by bifunctional thioureas, solvent catalysis by fluorinated alcohols in epoxidation by hydrogen peroxide, and intra-molecular cooperative hydrogen bonding in trans-a,a -(dimethyl-l,3-dioxolane-4,5-diyl)bis(diphenyl methanol) (TADDOL) (7)-type catalysts. ... 

For a general review of chiral H-bond donars in asymmetric catalysis including Jacobsen type thiourea catalyzed reactions, see the following articles and references cited within [R]... 

Much of this introductory section is taken from our review on the same subject that appeared in the earher edition of this volume [1]. Chiral phosphoric acids and chiral thioureas, each representing a major subdivision of hydrogen bonding catalysis, are discussed in separate chapters, the former by Professor Aldyama (Chapter 11) and the latter by Professor Schreiner (Chapter 12). 

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