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Several modifications of alkynylation reactions are known: In the Arens–van Dorp synthesis the compound ethoxyacetylene [7] is converted to a Grignard reagent and reacted with a ketone, the reaction product is a propargyl alcohol. [8] [9]
The reaction was discovered in the early 1900s by the Russian chemist Alexei Yevgrafovich Favorskii. [1] Favorskii reaction and the possible subsequent rearrangement. When the carbonyl is an aldehyde (R"=H), a rearrangement can occur to generate enone, although the secondary propargylic alcohol can be isolated in some cases. [2]
Similar reactions occur when tertiary phosphines are treated with alkyl halides, the products being phosphonium salts. Menshutkin-reaction. Thiols are readily alkylated to give thioethers via the thiol-ene reaction. [4] The reaction is typically conducted in the presence of a base or using the conjugate base of the thiol.
The alkynylation reaction of aryl halides using aromatic acetylenes was reported in 1975 in three independent contributions by Cassar, [4] Dieck and Heck [5] as well as Sonogashira, Tohda and Hagihara. [6] All of the reactions employ palladium catalysts to afford the same reaction products.
This alkynylation reaction is enantioselective and involves an alkynylzinc reagent [1] rather than the sodium acetylide used by John Ulric Nef in his 1899 report of the synthetic approach. [ 2 ] [ 3 ] Propargyl alcohols are versatile precursors for the chirally-selective synthesis of natural products and pharmaceutical agents , making this ...
The photo-Favorskii reaction has been used in the photochemical unlocking of certain phosphates (for instance those of ATP) protected by p-hydroxyphenacyl groups. [13] The deprotection proceeds through a triplet diradical ( 3 ) and a dione spiro intermediate ( 4 ) although the latter has thus far eluded detection.
The Corey–Fuchs reaction, also known as the Ramirez–Corey–Fuchs reaction, is a series of chemical reactions designed to transform an aldehyde into an alkyne. [1] [2] [3] The formation of the 1,1-dibromoolefins via phosphine-dibromomethylenes was originally discovered by Desai, McKelvie and Ramirez. [4]
The metal-catalyzed reaction, on the other hand, is energetically reasonable and probably occurs via a stepwise hydride transfer to the alkyne followed by C–N bond scission in a process similar to those proposed for formal [3,3]-sigmatropic rearrangements and hydride transfer reactions catalyzed by gold(I) complexes. [12]