New Reagent for Convenient Access to the α,β‐Unsaturated N‐Methoxy‐N‐methyl‐amide Functionality by a Synthesis Based on the Julia Olefination Protocol.

Manjunath, B. N.; Sane, Neeraj; Aidhen, Indrapal Singh

doi:10.1002/chin.200641056

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“…LHMDS (1.0 M in THF) was obtained from commercial sources. Julia Kocienski reagent 2-(benzo[ d ]thiazol-2-ylsulfonyl)-2-fluoro- N -methoxy- N -methylacetamide ( 1 ) was prepared from the known 2-(benzo[ d ]thiazol-2-ylsulfonyl)- N -methoxy- N -methylacetamide [ 54 ], via metalation-fluorination using our previously reported procedure [ 31 ]. All other reagents were obtained from commercial sources and used without further purification.…”

Section: Methodsmentioning

confidence: 99%

Synthesis of Regiospecifically Fluorinated Conjugated Dienamides

et al. 2014

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Modular synthesis of regiospecifically fluorinated 2,4-diene Weinreb amides, with defined stereochemistry at both double bonds, was achieved via two sequential Julia-Kocienski olefinations. In the first step, a Z-α-fluorovinyl Weinreb amide unit with a benzothiazolylsulfanyl substituent at the allylic position was assembled. This was achieved via condensation of two primary building blocks, namely 2-(benzo[d]thiazol-2-ylsulfonyl)-2-fluoro-N-methoxy-N-methylacetamide (a Julia-Kocienski olefination reagent) and 2-(benzo[d]thiazol-2-ylthio)acetaldehyde (a bifunctional building block). This condensation was highly Z-selective and proceeded in a good 76% yield. Oxidation of benzothiazolylsulfanyl moiety furnished a second-generation Julia-Kocienski olefination reagent, which was used for the introduction of the second olefinic linkage via DBU-mediated condensations with aldehydes, to give (2Z,4E/Z)-dienamides in 50%–74% yield. Although olefinations were 4Z-selective, (2Z,4E/Z)-2-fluoro-2,4-dienamides could be readily isomerized to the corresponding 5-substituted (2Z,4E)-2-fluoro-N-methoxy-N-methylpenta-2,4-dienamides in the presence of catalytic iodine.

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Section: Methodsmentioning

confidence: 99%