Host: Division of Organic Chemistry, The Pharmaceutical Society of Japan
Pages 24-25
Ethynyl(phenyl)(tetrafluoroborato)-λ3-iodane (1) serves as an efficient Michael acceptor, but its synthetic application is limited due to the low thermal stability. We found that the λ3-iodane (1) forms the supramolecular 1:1 complex (2) with 18-crown-6 in a high yield and the complexation dramatically increased the stability of the labile λ3-iodane (1). Solid state structure with pentacoordinated iodine(III) was determined by X-ray analysis and solution structure was examined by 1H NMR and CSI–MS, and binding constant was measured. The complex (2) holds for the high reactivity toward attack of nucleophiles and serves as a direct ethynylation agent for enolate anions, sulfinates, and phosphites. The 18-crown-6 ligand in (2) makes it possible to synthesize the highly labile (Z)-(β-alkoxyvinyl)phenyl-λ3-iodanes, which have never been synthesized, as a crown ether complex.
