Butadiyne, nucleophilic addition

Nucleophilic additions of alcohols, amines, thiols, and selenols to Group 8 buta-trienylidene intermediates [M]=C=C=C=CR2 have also been used in the preparation of stable heteroatom-conjugated allenylidene complexes. Thus, activation of trimethylsilyl-l,3-butadiyne HC=C-C=CSiMe3 by the iron(II) complex [FeClCp (dppe)], in methanol and in the presence of NaBPh4, resulted in the high-yield formation of the methoxy-allenylidene [FeCp =C=C=C(OMe)Me ... 

When both hydrogens of butadiyne are replaced by methyl groups the reactivity toward nucleophilic addition drops substantially and more drastic conditions are required. Addition of methanol to 2,4-hexadiyne (102, n = 2) requires the use of concentrated alkali at temperatures above 100 °C to give 103 (R = Me) = addition... 

Polymerization has been attempted b conventional free radical, cationic and anionic initiators. Reactivity was observed, but a well defined polymer structure was not characterized. Butadiyne has been reported to fonj condensation copol3r-mers b nucleophilic addition of diamines or heterocyclic compounds. From its structure as the simplest diacetylene, it would be expected to figure prominently in solid state diacetylene polymerizations (Eq. 1). In one instance Wegner does... 

Vinyl azides were seldom prepared by nucleophilic addition at alkynes lacking in strongly electron-withdrawing groups. Thus, the reaction of butadiyne (24) with lithium azide in methanol is such a rare case, which allows the isolation of enyne 25 as a yellow liquid. ... 

This rarer, and rather surprising, approach to Z-alkenes sometimes gives excellent results particularly in the addition of nucleophiles to butadiyne. The base-catalysed addition of methanol gives an... 

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