One-pot synthesis of spiro[adamantane-2,2′-boriranes] via the Cp₂TiCl₂-catalyzed cycloboration of methyleneadamantane with boron halides

A new one-pot method for the synthesis of earlier unknown boron-containing adamantane derivatives, spiro[adamantane-2,2′-boriranes], via the catalytic cycloboration of methyleneadamantane with BF₃·THF and RBCl₂·SMe₂ (R is 2-norbornyl and cyclooctyl) in the presence of Cp₂TiCl₂ and Mg (acceptor of halide ions) was developed. The structure of spiro[adamantane-2,2′-boriranes] was elucidated using 1D (¹H, ¹³C, ¹¹B, and ¹⁹F) and 2D (HSQC, HMBC, COSY, and diffusion-ordered (DOSY)) NMR techniques. 1-Fluorosubstituted spiro[adamantane-2,2′-borirane] was identified as a complex with the solvent molecule (THF) according to a comparison of the experimental and calculated ¹¹B NMR chemical shifts and the calculation data for the thermodynamic parameters of complex formation.