The synthesis and chemistry of novel Lewis acids containing neutral tin-centered Lewis acidic groups at the 2-and 2′-positions of 1.1′-binaphthyl are described. (±)-2,2′-Dibromo-1,1′-binaphthyl (3) was converted to the dilithio derivative, which was treated with trimethyltin chloride to yield 2,2′-bis(trimethyl-stannyl)-1,1′-binaphthyl (4) in excellent yield. Compound 4 then underwent highly selective methyl-Sncleavage in the redistribution reactions with methyltin trichloride and tin tetrachloride to afford 2,2′-bis(monochlorodimethylstannyl)-and 2,2′-bis(dichloromethylstannyl)-1,1′-binaphthyl, 2a and 2b, respectively. The chlorotins were then converted into the organotin triflates, 2c and 2d, by metathetic reactions with silver triflate. Interaction of the bis(dichlorotin) 2b and DMSO afforded a mono-DMSO (12) whose X-ray crystal structure revealed that coordination of DMSO occurred to one tin center and a chloride ligand from this tin had bridging interaction with the other tin moiety. An estimation of the equilibrium constant for the formation of 12 was obtained by 119Sn NMR spectroscopy.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry