Mechanistic definition of trimethylstannylation of 1,3-dihaloadamantanes: delocalized radical anions as possible intermediates

Abstract

A series of 1,3-dihaloadamantanes (3, X=Y=halogens) have been synthesized, characterized, and treated with (trimethylstannyl) alkali reagents (Me 3 SnM, M=Li or Na) in the absence and presence of tert-butylamine (TBA) and dicyclohexylphosphine (DCPH). The product distributions of these reactions have been established by 13 C and 119 Sn NMR spectroscopy and vapor-phase chromatographic analyses. Tin substitution via an S RN 1-type pathway is shown to be a significant reaction for several of the derivatives of 3 (X=F, Y=Br or I; X: Cl, Y=Br or I; X= Y=Br) but not for the bromo iodide or diiodide (3, X=Br, Y=I and X=Y=I)