Migration acetylide groups

Addition of acid to the /i3-acetylide complexes (92 M = Ru or Os) results in the formation of 93 (M = Ru or Os) by an acid-induced migration of the hydroxy group from carbon to metal (137). Only the orange osmium derivative could be isolated, and this was structurally characterized as the /i3-di phenylpropadienylidene complex shown. 

It has been found that monosubstituted acetylenes can be obtained by Brown s method (equation 164) only when lithium acetylide is replaced by the lithium acetylide-ethylenediamine complex. High yields of terminal alkyl and cycloalkyl-acetylenes are obtained. It has also been demonstrated that the migration of an alkyl group proceeds with retention of configuration, as shown in equation (168). ... 

Lithium ethynyltrialkylborates synthesis of methyl ketones. Lithium acetylide reacts with trialkylboranes at -78° (THF) to give lithium ethynyltrialkylborates (1). On treatment with hydrochloric acid one alkyl group migrates from boron to carbon to give (2). A second migration is prevented by addition of base (also at -78°). Oxidation of (2) then gives a methyl ketone... 

Hydroboration of 1-hexyne with dicyclohexylborane produced the alkenylborane 55, which on treatment with the lithium acetylide 56 furnished the organoborate complex 57 (Scheme 14) (24). Trimethyltin chloride then induced a stereoselective migration of the 1-hexenyl group to the adjacent acetylenic carbon to afford the diene-allene 58 and subsequently the o-isotoluenes 59 and 60. A variety of other o-isotoluenes were likewise synthesized. 

---