SYNTHESIS OF 1,4DI(N-PYRIDYL)BUTA-1,3-DIYNE AND FORMATION OF CHARGE-TRANSFER COMPLEXES - X-RAY STRUCTURE OF 1,4-DI(3-PYRIDYL)BUTA-1,3-DIYNE

Ethynylpyridines have been satisfactorily prepared by two different ro utes: (a) the Wittig reaction between chloromethylene(triphenyl)phosph ine ylide and a pyridinecarbaldehyde, followed by elimination of hydro gen chloride; (b) from the 2-methyl-4-(n-pyridyl)but-3-yn-2-ol interme diate, by elimination of acetone. 1,4-Di(n-pyridyl)buta-1,3-diynes are obtained by oxidative dimerization in good yield. An X-ray structure of the 3-substituted dimer is reported. Mono- and di-methyl salts of t he 3-substituted diyne have been obtained and the charge-transfer comp lexes with tetramethyl-p-phenylenediamine (TMPD) are formed.