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A U‐Turn in the Asymmetric Appel Reaction: Stereospecific Reduction of Diastereomerically Enriched Alkoxyphosphonium Salts Allows the Asymmetric Synthesis of P ‐Stereogenic Phosphanes and Phosphane Boranes
Author(s) -
Rajendran Kamalraj V.,
Kudavalli Jaya S.,
Dunne Katherine S.,
Gilheany Declan G.
Publication year - 2012
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201200285
Subject(s) - chemistry , stereocenter , boranes , stereospecificity , diastereomer , yield (engineering) , organic chemistry , stereochemistry , combinatorial chemistry , enantioselective synthesis , medicinal chemistry , catalysis , boron , materials science , metallurgy
An efficient one‐pot synthesis has been developed of enantioenriched P ‐stereogenic phosphanes and phosphane boranes from the corresponding racemic phosphanes in excellent yield under asymmetric Appel conditions. The chiral auxiliary (menthol) can also be recovered unchanged. The simple and efficient protocol significantly expands the scope of our asymmetric Appel process. The crucial step in the preparation involves stereospecific reduction of intermediate diastereomeric alkoxyphosphonium salts, which are obtained in the reaction of phosphane, hexachloroacetone, and menthol. Thereby, reaction with LiAlH 4 or NaBH 4 gives the corresponding phosphanes or phosphane boranes, respectively.