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An Expedient and Stereoselective Synthesis of Alkenyl Nonaflates from Silyl Enol Ethers: Optimization, Scope and Limitations
Author(s) -
Lyapkalo Ilya M.,
Webel Matthias,
Reißig HansUlrich
Publication year - 2002
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200203)2002:6<1015::aid-ejoc1015>3.0.co;2-k
Subject(s) - chemistry , enol , potassium fluoride , silylation , fluoride , organic chemistry , stereoselectivity , catalysis , silyl enol ether , molecular sieve , medicinal chemistry , enol ether , inorganic chemistry
The fluoride‐catalysed reaction between silyl enol ethers 1 and nonafluorobutanesulfonyl fluoride (NfF) has been optimized, resulting in an expedient synthesis of the corresponding alkenyl nonaflates 3 . Tetra‐ n ‐butylammonium fluoride, dried either with molecular sieves or with potassium fluoride, and potassium fluoride in the presence of dibenzo‐18‐crown‐6 were the best and most practical catalysts for this process. The reaction allows the synthesis of a wide variety of cyclic and acyclic alkenyl nonaflates 3 in good to excellent yields. For E / Z isomeric alkenes the configuration of the double bond is essentially retained. Remarkably, enolates derived from methyl ketones also provide C ‐sulfonylation products 4 as a side product; the desired alkenyl nonaflates 3l and 3m could, however, be prepared in good yields by further optimization. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)