But-2-yne-l,4-diol

But-3-en-2-one, 1,1, l-trifluoro-4-(2-thienyl)-4-mercapto-liquid—liquid extraction, 1, 544 Butex process, 6, 938 But-2-yne-l,4-diol hydrogenation... 

The oxidation of propargyl alcohol to the acid and of but-2-yne-l,4-diol to acetylene dicarboxylic acid is carried out on a technical scale at a lead dioxide anode in sulphuric acid [4, 5]. Electrochemical oxidation of acetylenic secondary alcohols to the ketone at lead dioxide in aqueous sulphuric acid [4], gives better results than the cliromic acid based process of Jones [6], Oxidation of aminoalkan-1-ols to the amino acid at a lead dioxide anode in sulphuric acid is achieved in 31 -73 % 5delds [7]. This route is applied to the technical scale production of (l-alanine from 3-aminopropanol in an undivided cell [8]. 

Z)-But-2-ene-l,4-diol.24 But-2-yne-l,4-diol (20g) is dissolved in methanol (350ml) and hydrogenated at atmospheric pressure in the presence of 0.5 per cent palladium-on-calcium-carbonate (2.0 g). After 24 hours one equivalent of hydrogen (5650 ml) will be absorbed. The catalyst is then separated and the filtrate distilled, giving (Z)-but-2-ene-l,4-diol as a colourless oil (15.7g, 77%), b.p. 134-135 °C/15 mmHg, n 5 1.4716. The product forms a dibenzoate (prisms from aqueous methanol), m.p. 69-70 °C. 

Butyne-l,4-diol derivatives undergo dicarbonylation of different types. A simple synthetic method of bis(methylene)succinate 78 is the carbonylation of the dicarbonate of but-2-yne-l,4-diol (77) at 50°C [20]. 

The transformation of enantiomerically enriched 1,1,4-trisubstituted but-2-yne-l,4-diols (262) into 2,2,5-trisubstituted 3-acyloxy-2,5-dihydrofurans (267) with complete stereospecificity has been achieved by an Ag(I)-mediated rearrangement of the monoesters (263) to allenic intermediates (265), followed by Ag(I)-assisted cycUzation. A possible mechanism for the rearrangement and cyclization is shown in Scheme 66, in which the carbon-oxygen bond (b) in (266) is formed from the back side of the carbon-oxygen bond (a) in (264). A novel synthetic method has been developed for the rearrangement of 3-aryl-l,2-dialkynylallyl alcohols into m-enediynes under mild acidic conditions. The allylic rearrangement has been shown to involve an acid-catalysed isomerization step to convert the allyl alcohol into an allylic cation... 

The lack of regiocontrol during the hydration of triple bonds in substituted but-2-yne-l,4-diols has meant that they are not especially useful for the construc-... 

In the coupling reaction of tetrayne 2.82 with but-2-yne-l,4-diol 2.60f in the presence of the complex IrCl(cod)]2-CHIRAPHOS [2,3-bis(diphenylphosphino)butane)j the high diastereoselectivity was achieved only with TBS-protection ( -BuMe2Si) of the hydroxy group (Scheme 2.28) [61, 63]. 

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