A straightforward synthesis of tetra and trialkynylgermanes by reactions of compounds containing Ge-N or Ge-Cl bonds with alk 1 ynes was proposed. Reactions of appropriate amino or halogermanes with alk 1 ynes were effective only in the presence of an equivalent amount of zinc dihalide.Acetylene derivatives of germanium, in which the Ge atom is bound to sp hybridized C atoms, are well known and are conventionally synthesized by reactions of alkali metal or magnesium alkynides with halogermanes. 1,2However, direct replacement of the acid H atom in alk 1 ynes by germanium has been reported for only a few cases, 3,4 in contrast to similar reactions of alk 1 ynes with compounds containing Sn-Cl, 5 Sn-O, 6 Sn-N, 7 and Pb-O bonds. 8 Earlier, 9 we have shown that dialkylamino silanes react with alk 1 ynes in the presence of zinc dihalides to give silylalkynes in high yields.Here we found that reactions of tetrakis(dialkyl amino)germanes 1 and tris(dialkylamino)phenylgermanes 2 with alk 1 ynes 3 in dioxane or THF at 70-100 °C in the presence of zinc dihalides afford alkynylgermanes in high yields (Scheme 1; Tables 1, 2). Scheme 1 n = 0; NR 2 2 = NEt 2 (1a), N(CH 2 ) 5 (1b); R 3 = Bu (3a, 4a), Me 3 Si (3b, 4b), Ph (3c, 4c), CH 2 OAc (3d, 4d), C 6 H 13 (3e, 4e), 4 BrC 6 H 4 (3f, 4f); 1 C 10 H 7 (3g, 4g); n = 1; R 1 = Ph; NR 2 2 = NEt 2 (2a), N(CH 2 ) 5 (2b); R 3 = Bu (3a, 5a), Me 3 Si (3b, 5b), Ph (3c, 5c);
Hal = Cl, BrWith an excess of the acetylene component, three or four amino groups were exhaustively replaced in the reac tions with tris(dialkylamino)phenylgermanes 2 or tetra kis(dialkylamino)germanes 1, respectively. In the absence of zinc dihalides, the reaction did not occur even at el evated temperatures. This distinguishes tri and tetra aminogermanes from trialkyl(amino)germanes, which react with alk 1 ynes at 150-180 °C for a long time. 3,4The starting tris and tetrakis(dialkylamino)germanes are easily accessible via reactions of secondary amines with appropriate halogermanes. 14 When used in excess, these amines serve as a reaction medium and provide virtually quantitative yields of aminogermanes 1 and 2.We also found that germanium tetrachloride and trichloro(phenyl)germane in the presence of zinc dihalides react with alk 1 ynes differently from what has been re ported earlier. 15 The presence of zinc dihalide increases the alkynylation degree and allows one to obtain tetra alkynylgermanes from germanium tetrachloride and trialkynyl(phenyl)germane from trichloro(phenyl)ger mane (Scheme 2). Scheme 2 n = 0; R 2 = Me 3 Si (3b, 4b), Ph (3c, 4c), CH 2 OAc (3d, 4d); n = 1; R 1 = Ph; R 2 = Bu (3a, 5a), Me 3 Si (3b, 5b), Ph (3c, 5c)The yields of tetraalkynylgermanes 4 and trial kynyl(phenyl)germanes 5 were up to 85 and 75%, respec tively. We found this method to be inapplicable to trialkylchlorogermanes and dialkyl(dichloro)germanes: they did not react with alk 1 ynes in the presence of
