Dienes, catalytic hydrogenation carbon monoxide

Conjugated dienes can add hydrogen by 1,2 or 1,4 addition. Selective 1,4 addition can be achieved by hydrogenation in the presence of carbon monoxide, with bis(cyclopentadienyl)chromium as catalyst. With allenes catalytic hydrogenation usually reduces both double bonds. 

Homologation of olefins by four carbon atoms is achieved by reaction of the derived borane (265) with buta-1,3-diene monoxide in the presence of catalytic amounts of oxygen. Trialkylboranes are also converted into the 4,4-dialkyl-c/j-but-2-ene-l,4-diols (266) in good yields by addition to a-lithiofuran and oxidation of the intermediate boroxarocyclohexenes (267) with hydrogen peroxide. ... 

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