Asymmetric Synergy Between Chiral Dienes and Diphosphines in Cationic Rh(I)-Catalyzed Intramolecular [4 + 2] Cycloaddition
Department of Applied Chemistry, Tokyo Institute of Technology, Edo, Tōkyō, JapanJournal of the American Chemical Society (Impact Factor: 12.11). 11/2006; 128(39):12648-9. DOI: 10.1021/ja0650100
High enantioselective [4 + 2] cycloaddition can be achieved by cationic Rh complexes bearing not only chiral phosphine but also chiral diene. This is the first example of asymmetric synergy between chiral dienes and diphosphines.
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ABSTRACT: This review intends to highlight the role of phosphorus ligands as chiral auxiliaries in enantioselective enyne cycloisomerizations. A few examples of cycloisomerizations involving polyunsaturated substrates are also discussed. Cycloisomerizations processes are known to follow a variety of reaction pathways according to the nature of the starting materials and the metal used as the catalyst. This implies a specific catalyst design for each class of reactions. Bidentate C2-symmetric diphosphines are the preferred chiral auxiliaries in rhodium and palladium promoted Alder-ene type cyclizations, which are so far the most deeply investigated enantioselective processes. Also, enantioselective variants of cyclizations involving electrophilic activation of the alkyne unit have been reported recently. They have been carried out under Ir, Pt and Au catalysis, by using both bidentate and monodentate chiral phosphines as the ligands. Overall, this literature overview points out the very early stage of development of the field.ChemInform 01/2011; 43(9). DOI:10.1007/978-90-481-3817-3_10
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ABSTRACT: The major progress in organic synthesis since 2005 is briefly surveyed in two parts. The first part deals with some of the most impressive advances in the synthetic methodology, which includes: (1) metal-mediated synthetic reactions, with an emphasis on the olefin metathesis and gold-mediated reactions; (2) free radical-based organic synthesis; (3) synthetic transformations performed in a “one-pot” manner involving either tandem reactions or multicomponent reactions; (4) asymmetric reactions catalyzed by metal and organo-catalysts. The major advances in total synthesis of some complex natural products with significant biological activities are presented in the second part, with detailed illustrations of ten selected molecules, including dragmacidin F, abyssomicin C, 11-acetoxy-4-deoxyasbestinin D, pentacycloanammoxic acid, UCS1025A, (−)-merrilactone A, nigellamine A2, (+)-saxitoxin, and Tamiflu (an artificially designed natural product-like molecule). An array of complicated structures of the natural products synthesized over the last two years is also listed to serve as a convenient lead to the original literature for the prospective interested readers.Frontiers of Chemistry in China 06/2007; 2(3):227-264. DOI:10.1007/s11458-007-0046-0
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