title: Synthesis and applications of chiral organoboranes generated from sulfonium ylides.
abstract: The reactions of aryl-stabilized sulfonium ylides with trialkyl/triarylboranes have been investigated. Clean monohomologation of the boranes with only a small amount of the higher homologation products (<10%) was observed. The homologation products were isolated as the alcohols (treatment with H2O2/NaOH) and amines (treatment with NH2OSO3H). Although the reactions were conveniently conducted at 5 degrees C, the ylide reaction with tributylborane was very fast even at -78 degrees C (complete after 15 min). Use of chiral sulfides rendered the reactions asymmetric, and high enantioselectivity (>95% ee) was observed in all cases. The ylide-borane reaction was applied to short syntheses of the anti-inflammatory agents neobenodine and cetirizine, both of which contain a chiral diarylmethylalkoxy and diarylmethylamino moiety, respectively.
authors.affiliation: School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K. v.aggarwal@bristol.ac.uk
authors.forename: Varinder K
authors.initials: VK
authors.lastname: Aggarwal
authors.forename: Guang Yu
authors.initials: GY
authors.lastname: Fang
authors.forename: Andreas T
authors.initials: AT
authors.lastname: Schmidt