a-Fluorovinyl Weinreb Amides and a-Fluoroenones from a Commom Fluorinated Building Block

Title
a-Fluorovinyl Weinreb Amides and a-Fluoroenones from a Commom Fluorinated Building Block
Authors
아룬 고쉬샤이발 바네리샤켓 쉬하강순방바바라 작
Keywords
Julia olefination; condensation reaction; Weinreb amide; olefination reaction; DBU; α-fluorovinyl; α-fluoroenone
Issue Date
2009-03
Publisher
Journal of organic chemistry
Citation
VOL 74, 3689-3697
Abstract
Synthesis and reactivity of N-methoxy-N-methyl-(1,3-benzothiazol-2-ylsulfonyl)fluoroacetamide, a building block for Julia olefination, is reported. This reagent undergoes condensation reactions with aldehydes and cyclic ketones to give R-fluorovinyl Weinreb amides. Olefination reactions proceed under mild, DBUmediated conditions, or in the presence of NaH. DBU-mediated condensations proceed with either E- or Z-selectivity, depending upon reaction conditions, whereas NaH-mediated reactions are ≥98% Z-stereoselective. Conversion of the Weinreb amide moiety in N-methoxy-N-methyl-(1,3-benzothiazol-2- ylsulfanyl)fluoroacetamide to ketones, followed by oxidation, resulted in another set of olefination reagents, namely (1,3-benzothiazol-2-ylsulfonyl)fluoromethyl phenyl and propyl ketones. In the presence of DBU, these compounds react with aldehydes tested to give α-fluoroenones with high Z-selectivity. The use of N-methoxy-N-methyl-(1,3-benzothiazol-2-ylsulfanyl)fluoroacetamide as a common fluorinated intermediate in the synthesis of α-fluorovinyl Weinreb amides and α-fluoroenones has been demonstrated. Application of the Weinreb amide to α-fluoro allyl amine synthesis is also shown.
URI
http://pubs.kist.re.kr/handle/201004/36619
ISSN
0022-3263
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KIST Publication > Article
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