title: Synthesis and reactivity of conformationally locked alpha-aminoorganostannanes and alpha-aminoorganolithiums. Discovery of a surprising configurational requirement for transmetalation.
abstract: [equation--see text] 2-Tributylstannyl-N-methylpiperidines that are conformationally locked by a 4-tert-butyl substituent were evaluated in transmetalations (Sn-Li exchange) and reactions with electrophiles. When the tin is equatorial, transmetalation occurs smoothly as does reaction with carbonyl electrophiles. Alkyl halides seem to undergo single electron transfer reactions, affording nonselective alkylation products, along with products of radical disproportionation. In a surprise, an axially oriented tin failed to transmetalate, suggesting that a synclinal relationship between the nitrogen lone pair and the carbon-tin bond is a requirement for transmetalation.
authors.affiliation: Department of Chemistry, University of Miami, Coral Gables, Florida 33124, USA.
authors.forename: G
authors.initials: G
authors.lastname: Chambournier
authors.forename: R E
authors.initials: RE
authors.lastname: Gawley
mesh_terms: D008094:Lithium / Q000737:chemistry*; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry / Q000378:metabolism*; D009947:Organotin Compounds / Q000737:chemistry* / Q000378:metabolism; D010880:Piperidines / Q000737:chemistry
chemical_list: D009942:Organometallic Compounds; D009947:Organotin Compounds; D010880:Piperidines; D008094:Lithium