ketones are generated in moderate yields (50–60%) from allene or a mono-, di- or tri-substitutedallenic hydrocarbon, n alkyl halide and sodium tetracarbonylferrate. The first step is the formation of a complex anion which results from transfer of the alkyl group on a coordinated CO, then of the acyl ligand thus formed on the allenic sp carbon. Protonation with acetic acid yields a hydroxy-η4-trimethylenemethane
enantioselective synthesis of the C3C9 fragment of Octalactin A and studies aimed at the conversion of Octalactin B into Octalactin A are described, which are based on the borane-mediated reduction of α,β-unsaturated ketones catalysed by B-methyl-4,5,5-triphenyl-1,3,2-oxaza-borolidines (9). A comparativestudy of the reduction of 2-methylnon-1-en-3-one (10) —a model of the Octalactin-A C3C9 moiety— with
Insertion d'allene dans une liaison fer-acyle. Formation de cetones α,β-insaturees a partir du tetracarbonyl ferrate de sodium
作者:A. Guinot、P. Cadiot、J.L. Roustan
DOI:10.1016/s0022-328x(00)90144-x
日期:1977.3
Disodium tetracarbonylferrate(−II) reacts with alkyl bromides and allene to yield α,β-unsaturated ketones. It is suggested that the reaction proceeds throughinsertion of “allene” into an ironacyl bond to yield an anionic intermediate which gives a π-heterobutadiene complex after protonation. Oxydation with trimethylamine oxide ultimately yields the ketone.
Boron Trifluoride Etherate Mediated 1,4-Addition of (1-Alkynyl)diisopropoxyboranes to α,β-Unsaturated Ketones. A Convenient New Route to 3-Alkynyl Ketone Synthesis
In the presence of BF3 etherate, (1-alkynyl)diisopropoxyboranes react with α,β-unsaturatedketones to give 1,4-addition products selectively in good yields.
α-Methoxyallyl sulfides prepared from methoxy(phenylthio)methane proved to be a novel acylanionequivalent providing a new synthetic method for α-methylenated ketones.