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DOI: 10.1055/s-2008-1078005
Synthesis of Substituted Enol Ethers and Their Synthetic Application
Rezensent(en):Hisashi Yamamoto, Cheol Hong CheonThe University of Texas Southwestern Medical Center at Dallas, USA
Preparation of Substituted Enol Derivates from Terminal Alkynes and Their Synthetic Utility
J. Am. Chem. Soc. 2008, 130: 7828-7829
Publikationsverlauf
Publikationsdatum:
22. August 2008 (online)
Key words
enol derivatives - methylalumination -
Significance
The authors describe the preparation for trisubstituted enol derivatives via tandem carbometalation-oxygenation of terminal alkynes. The enol derivatives were isolated as a single regioisomer with a high E-selectivity (E/Z > 20:1). Stereodefined enol ethers can undergo asymmetric dihydroxylation to yield optically active α-hydroxy aldehydes. Finally, α-hydroxy aldehydes were shown to undergo homologation to a terminal alkyne, reductive amination, oxidation and olefination.
Comment
Recently, the Ready group reported carbocupration-oxygenation of terminal alkynes as an alternative method for trisubstituted enol derivatives (Org. Lett. 2005, 7, 5681). However, methyl-substituted products were not accessible by this method because of inefficient methyl-cupration of alkynes. In this paper, they described a general method for obtaining methyl-substituted enol ether and explored the asymmetric transformations of stereodefined enol derivatives. Although it is a simple idea, it works nicely. This method will have broad utility in the future.