title: Stereodivergent SN2@P reactions of borane oxazaphospholidines: experimental and theoretical studies.
abstract: The stereodivergent ring-opening of 2-phenyl oxazaphospholidines with alkyl lithium reagents is reported. N-H oxazaphospholidines derived from both (+)-cis-1-amino-2-indanol and (-)-norephedrine provide inversion products in a highly stereoselective process. In contrast, N-Me oxazaphospholidines yield ring-opening products with retention of configuration at the P center, as previously reported by Jugé and co-workers. As a result, from a single amino alcohol auxiliary, both enantiomers of key P-stereogenic intermediates could be synthesized. Theoretical studies of ring-opening with model oxazaphospholidines at the DFT level have elucidated the streochemical course of this process. N-H substrates react in a single step via preferential backside S(N)2@P substitution with inversion at phosphorus. N-methylated substrates react preferentially via a two-step frontside S(N)2@P, yielding a ring-opened product in which the nucleophilic methyl binds to P with retention of configuration. DFT calculations have shown that the BH3 unit is a potent directing group to which the methyl lithium reagent coordinates via Li in all the reactions studied.
authors: Department of Theoretical Chemistry, Amsterdam Center for Multiscale Modeling, VU University Amsterdam, De Boelelaan 1083, NL-1081 HV Amsterdam, The Netherlands.
authors: Hester
authors: H
authors: Zijlstra
authors: Thierry
authors: T
authors: León
authors: Abel
authors: A
authors: de Cózar
authors: Célia
authors: C
authors: Fonseca Guerra
authors: Daniel
authors: D
authors: Byrom
authors: Antoni
authors: A
authors: Riera
authors: Xavier
authors: X
authors: Verdaguer
authors: F Matthias
authors: FM
authors: Bickelhaupt
mesh_terms: D001555:Benzene Derivatives / Q000737:chemistry*; D001880:Boranes / Q000737:chemistry*; D007189:Indans / Q000737:chemistry; D008094:Lithium / Q000737:chemistry; D008958:Models, Molecular; D010080:Oxazoles / Q000737:chemistry*; D010665:Phenylpropanolamine / Q000737:chemistry; D010758:Phosphorus / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: C470122:(1,3,2)oxazaphospholidine; D001555:Benzene Derivatives; D001880:Boranes; D007189:Indans; D010080:Oxazoles; C116915:aminoindanol; D010758:Phosphorus; D010665:Phenylpropanolamine; D008094:Lithium