An improved, efficient route to 2,2-difluoroethenylbenzenes
摘要:
Treatment of vinylidene fluoride with tert-BuLi at - 115 degrees C gave a solution of [F2C=CHLi]. Addition of Bu3SnCl to this lithium reagent at - 110 degrees C gave an 88% isolated yield of F2C=CHSnBu3. Reaction of F2C=CHSnBu3 with substituted aryl iodides under Stille-Liebeskind conditions [Pd(PPh3)(4)/Cu(I)I] at room temperature afforded the 2,2-difluoroethenylbenzines in good yield. In the absence of the Cu(I)I co-catalyst, no reaction occurred. This work provides the most efficient route for the conversion of aryl halides to 2,2-difluorostyrenes. (C) 2011 Elsevier B.V. All rights reserved.
reported. By taking advantage of the in situ generated α-CF3-benzylsilver intermediates derivedfrom the nucleophilic addition of silver fluoride to gem-difluoroalkenes, this strategy bypasses the use of a strong base, thus enabling a mild and general synthetic method for ready access to non-symmetric α,α-disubstituted trifluoroethane derivatives.
Herein we present a novel strategy based on palladium-catalyzed allylic alkylation by taking advantage of the nucleophilic addition of external fluoride onto gem-difluoroalkenes as the initiation step. The merit of this protocol is highly appealing, as it enables a formal allylation of trifluoroethylarene derivatives through the in situ generation of β-trifluorocarbanions, which otherwise are deemed to
Regio- and Stereoselective Alkenylation of Allenoates with <i>gem</i>-Difluoroalkenes: Facile Access to Fluorinated 1,4-Enynes Bearing an All-Carbon Quaternary Center
作者:Qi-Qi Zhang、Shi-Yong Chen、E Lin、Honggen Wang、Qingjiang Li
DOI:10.1021/acs.orglett.9b00775
日期:2019.5.3
A regio- and stereoselective synthesis of fluorinated 1,4-enynes bearing an all-carbon quaternarycenter at the propargylic position is developed. The synthesis starts from readily available allenoates and gem-difluoroalkenes and proceeds via a key alkynylenolate intermediate following a nucleophilic addition/β-F elimination. This reaction occurs under mild reaction conditions with good tolerance to
Synthesis of 2,2-Difluorinated 4-Isoflavanols/4-Thioisoflavanols via a Base-Catalyzed [4 + 2] Annulation Reaction of <i>gem</i>-Difluoroolefins
作者:Jiaheng Li、Cong Xu、Na Wei、Mang Wang
DOI:10.1021/acs.joc.7b01635
日期:2017.11.3
DBU-catalyzed sequential intermolecular and intramolecular nucleophilic addition reactions between gem-difluoroolefins and o-hydroxy/mercapto benzaldehydes have been developed to provide a [4 + 2] annulation strategy for facile synthesis of gem-difluorinated isoflavanol derivatives. The competitive addition–elimination reaction of gem-difluoroolefins with nucleophiles was avoided under mild conditions,
Asymmetric Synthesis of 2,2‐Difluorotetrahydrofurans through Palladium‐Catalyzed Formal [3+2] Cycloaddition
作者:Jun Liu、Longhui Yu、Changwu Zheng、Gang Zhao
DOI:10.1002/anie.202111376
日期:2021.10.25
The asymmetricsynthesis of 2,2-difluorinated tetrahydrofurans was accomplished via enantioselective formal [3+2] cycloaddition catalyzed by palladium. The asymmetric reaction between gem-difluoroalkenes and racemic vinyl epoxides or vinylethylene carbonates resulted in the formation of enantioenriched 2,2-difluorotetrahydrofurans with an enantioselectivity up to 98 %. Notably, the reaction used the