Free and supported phosphorus ylides: efficient, neutral non-nucleophilic Bronsted bases with a wide utility in organic synthesis

The tris(dimethylamino)-C-dimethylphosphorus ylide and its supported versio n the tris(dimethylamino)-phosphorus ylide C-bound to Merrifield's resin ar e strong non-nucleophilic bases (the pK(a) value of the conjugate acid has bren estimated at 27 in THF). These compounds efficiently replace classical bases in the N-alkylation reaction of lactams, benzodiazepines, beta-amino phosphine oxides and alpha-amino acid derivatives. They can be involved in the C-alkylation reaction of benzodiazepines, imines, lactams, succinimide s, and beta-enamines. They can also be used in base-catalysed aldol-type co ndensation (Henry) reactions of nitroethane with aldehydes, and in olefinat ion reactions of phosphine oxides and phosphonates. (C) 2000 Academie des s ciences/Editions scientifiques et medicales Elsevier SAS.