Activation of 1,1-Difluoro-1-alkenes with a Transition-Metal Complex: Palladium(II)-Catalyzed Friedel–Crafts-Type Cyclization of 4,4-(Difluorohomoallyl)arenes
摘要:
Cationic palladium(II) ([Pd(MeCN)(4)](BF4)(2)) provides the first transition-metal-catalyzed method for electrophilic activation of electron-deficient 1,1-difluoro-1-alkenes, which allows their Friedel-Crafts-type cyclization with an intramolecular aryl group via a Wacker-type process. By using BF3 center dot OEt2, the cyclization was effected by a catalytic amount of the palladium without its reoxidation.
Development of a general copper-catalyzed vinylic Finkelstein reaction—application to the synthesis of the C1–C9 fragment of laingolide B
作者:Antoine Nitelet、Kévin Jouvin、Gwilherm Evano
DOI:10.1016/j.tet.2016.07.018
日期:2016.10
conditions compatible with a range of highly functionalized substrates. The potential of this vinylic halogen exchange reaction in total synthesis and medicinal chemistry was demonstrated by its successful use for the synthesis of the C1–C9 fragment of laingolide B and for the late-stage modification of drug-like molecules. The extension of this halogen exchange to the acetylenic and allenic Finkelstein
vinyl dichlorides and electron deficient amides as the starting material is described. In the absence of transition-metal catalyst, the reaction proceeds under mild reaction conditions in open air and thus rendering a convenient operation. This strategy is not only suitable for both terminal and internal ynamide synthesis but also amenable for large-scale preparation. Broad substrate scopes with respect
A new and practical synthesis of vinyl dichlorides via a non-Wittig-type approach
作者:Zhe Wang、Silvio Campagna、Guoyou Xu、Michael E Pierce、Joseph M Fortunak、Pat N Confalone
DOI:10.1016/s0040-4039(00)00547-5
日期:2000.5
A practical approach for the conversion of aldehydes to vinyl dichlorides has been developed. These are three-step, one-pot reactions involving the formation of trichlorocarbinol by treatment of aldehydes with trichloroacetic acid and sodium trichloroacetate followed by in situ protection and elimination reactions to form the desired vinyl dichlorides in 85 to 95% yields.
A convenient and straightforward strategy for the synthesis of 2,3-disubstituted and 2,3,5-trisubstituted furans via a base-promoted domino reaction of β-keto compounds with vinyl dichlorides is described. This transition-metal-free approach proceeds under operationally simple reaction conditions featuring easily available starting materials, a broad substrate scope, and good functional group tolerance
Process for the preparation of cyclopropylacetylene
申请人:——
公开号:US06359164B1
公开(公告)日:2002-03-19
The present invention relates generally to novel methods for the preparation of cyclopropylacetylene which is an essential reagent in the asymmetric synthesis of (S)-6-chloro-4-cyclopropylethynyl-4-trifluoromethyl-1,4-dihydro-2H-3,1-benzoxazin-2-one; a useful human immunodeficiency virus (HIV) reverse transcriptase inhibitor with superior anti-retroviral activity. In the process, for example, cyclopropane carboxaldehyde is alkylated to form 1,1,1-trichloro-2-cyclopropyl-ethanol; which in turn undergoes elimination to form 1,1-dichloro-2-cyclopropyl-ethene; which in turn undergoes elimination to form cyclopropyl acetylene.