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J Am Chem Soc

Title:		Preparation of substituted enol derivatives from terminal alkynes and their synthetic utility
Author(s):		DeBergh JR; Spivey KM; Ready JM;
Address:		"Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9038, USA"
Journal Title:		J Am Chem Soc
Year:		2008
Volume:		20080603
Issue:		25
Page Number:		7828 - 7829
DOI:		10.1021/ja803480b
ISSN/ISBN:		1520-5126 (Electronic) 0002-7863 (Print) 0002-7863 (Linking)
Abstract:		"Stereodefined enol derivatives of aldehydes are prepared from terminal alkynes. Specifically, terminal alkynes are known to undergo Cp2ZrCl2-catalyzed methylalumination. Here, we show that the resultant vinylalanes can be oxygenated with peroxyzinc species to generate trisubstituted enolates. Electrophilic trapping with carboxylic anydrides or silyl triflates yields trisubstituted enol esters or silanes, respectively. The tandem carbometalation/oxygenation tolerates free and protected alcohols, heterocycles, olefins, and nitriles. Stereodefined enol esters can undergo asymmetric dihydroxylation to yield optically active alpha-hydroxy aldehydes. Reduction with NaBH4 provides the diols of 1,1-disubstituted olefins in excellent ee. An application of this methodology to the enantioselective synthesis of the insect pheromone frontalin is presented. Finally, alpha-hydroxy aldehydes are shown to undergo homologation to a terminal alkyne, reductive amination, oxidation and olefination. Preliminary results indicate that tandem carbometalation/amination can be accomplished with azodicarboxylates. In this way, ene-hydrazines are formed in excellent yield"
Keywords:		Alcohols/chemical synthesis/*chemistry Alkenes/chemical synthesis/*chemistry Alkynes/*chemistry Hydroxylation Molecular Structure Stereoisomerism;
Notes:		"MedlineDeBergh, John R Spivey, Kathleen M Ready, Joseph M eng R01 GM074822/GM/NIGMS NIH HHS/ R01 GM074822-04/GM/NIGMS NIH HHS/ Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2008/06/04 J Am Chem Soc. 2008 Jun 25; 130(25):7828-9. doi: 10.1021/ja803480b. Epub 2008 Jun 3"