88533-70-4Relevant academic research and scientific papers
The synthesis of alkenes via epi-phosphonium species: 1. An anti-Wittig elimination
Lawrence, Nicholas J.,Muhammad, Faiz
, p. 15345 - 15360 (1998)
Anti-1,2-phosphinyl alcohols 11 and their corresponding syn-isomers upon treatment with phosphorus trichloride and triethylamine give E and Z alkenes respectively, by an anti elimination. This is in marked contrast to the syn Horner-Wittig elimination of the corresponding 1,2-phosphinoyl alcohols. The 1,2-phosphinyl alcohols 11 were prepared by the reduction of 1,2-phosphinoyl alcohols with cerium(III) chloride/lithium aluminium hydride. The anti elimination is explained by the formation of a transient epi-phosphonium species. An unexpected E-selective Horner-Wittig elimination during the cerium(III) chloride/lithium aluminium hydride reduction of a 1,2-phosphinoyl alcohol in which the diphenylphosphinoyl group is adjacent to an aryl group is described. This led to the synthesis of the antimitotic agent E- combretastatin A-4. An alternative synthesis of the 1,2-phosphinyl alcohols from the corresponding phosphine-borane complex is also described.
The Stereocontrolled Horner-Wittig Reaction: Synthesis of Disubstituted Alkenes
Buss, Antony D.,Warren, Stuart
, p. 2307 - 2326 (2007/10/02)
Addition of the lithium derivatives of phosphine oxides Ph2P(O)CH2R1 to aldehydes gives erythro adducts (11) with good stereoselectivity.Reduction of α-diphenylphosphinoyl ketones (12) gives threo adducts (11) with even better stereoselectivity.Purification by flash chromatography and/or crystallisation followed by elimination of Ph2PO2 gives pure Z- or E-alkenes with high material conversion.Explanations are offered for the stereoselectivities, conditions defined for full stereochemical control, and guidelines suggested for approaches to a given alkene.
CIS-OLEFINS FROM THE HORNER-WITTIG REACTION; ORIGIN AND OPTIMISATION OF STEREOCHEMISTRY
Buss, Antony D.,Warren, Stuart
, p. 3931 - 3934 (2007/10/02)
Conditions are described to produce high yields of erythro Horner-Wittig intermediates: stereospecific elimination gives cis-alkenes.
TRANS ALKENES BY STEREOSELECTIVE REDUCTION OF α-Ph2PO KETONES: E-ISOSAFFROLE, E-ANETHOLE, AND FENICULIN
Buss, Antony D.,Mason, Ralph,Warren, Stuart
, p. 5293 - 5296 (2007/10/02)
Conditions are described for the stereoselective reduction of α-Ph2PO ketones and stereospecific elimination from the resulting threo Horner-Witting intermediates to give pure E-alkenes such as the title compounds.
