Formation of 1,3-Diynes, 1,3-Dienes, and Biphenyls via the Copper(II) Nitrate Mediated Coupling of Organotin Compounds

Article abstract of DOI:10.1021/jo00228a026

A method for the preparation of symmetrically substituted 1,3-diynes, 1,3-dienes, and biphenyls based on the copper(II) nitrate mediated coupling of organotin compounds 1 (R = alkynyl, alkenyl, aryl) is described.The addition of alkynylstannane 1a, 1b, or 1c (a, R = THPOCH2C<*>; b, R = n-C4H9C<*>C; c, R = C6H5C<*>) to 1 equiv of Cu(NO3)2*3H2O in THF at 23 deg C afforded 1,3-diynes 2a-c in 85percent, 60percent, and 50percent yield, respectively.Similar treatment of alkenylstannanes 1d, 1e, 1f, or 1g (d, R = ; e, (E)-PhCH2OCH2CH=CH; f, (Z)-PhCH2OCH2CH=CH; g, 3,4-(CH3O)2C6H3C(=CH2)) afford to the 1,3-dienes 2d-g in 80percent, 72percent, 75percent, and 71percent yield, respectively.In the case of (E)- or (Z)-vinylstannanes, the dimerization process is found to be highly stereospecific.For example, copper(II) nitrate induced coupling of 1f (R = (Z)-PhCH2OCH2CH=CH) afforded a 23:1 ratio of (Z,Z)/(E,Z)-diene stereochemistry for 2f (R = PhCH2OCH2CH=CH).Also prepared by this method were the substituted biphenyls 2h-k (h, R = 4-CH3C6H4; i, R = 4-CH3OC6H4; j, R = 2-CH3OC6H4; k, R = 4-(CH3)-2,6-(CH3O)2C6H3) in 14-66percent yield.Aspects about the possible mechanism of dimerization are discussed.