Tetrasubstituted olefins, torquoselective

In contrast, the C-C triple bond shows excellent effect on torquoselectivity. Alkynyl aUcyl ketones 81 are olefinated by ynolates to afford the tetrasubstituted olefins 83 in good -selectivity (Fig. 28) [72]. In the electrocyclic reaction of 82, the alkynyl group prefers outward rather than inward rotation over the alkyl and alkenyl... 

Stereoselective synthesis of tetrasubstituted alkenes remains a challenging task. A unique solution to this problem is to use torquoselectivity-controlled oletina-tion of carbonyl compounds with ynolates, which is summarized in Chapter 1. In general, the stereoselective synthesis of Z-alkenes, which are thermodynamically less favorable, is more difficult than the synthesis of corresponding -isomers. In Chapter 2, various methods for stereoselective synthesis of Z-alkenes are reviewed. Finally, the C=C double bond formation through catalytic carbene transformation has recently emerged as a new approach toward olefin synthesis. Two chapters covering olefin synthesis based on catalytic carbene transformations are included (Chapter 5 and Chapter 8). 

Stereoselective Synthesis of Tetrasubstituted Alkenes via Torquoselectivity-Controlled Olefination of Carbonyl Compounds... 

Review Shindo M, Mori S. Torquoselective olefination of carbonyl compounds with ynolates highly efficient stereoselective synthesis of tetrasubstituted alkenes. Synlett 2008 2231-2243. 

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