Dienes, catalytic hydrogenation oxygen

Honma and Ban (307) have reported a second synthesis of deoxyaspidodispermine (158). Crucial in this scheme is the eosine-sensitized stereospecific addition of oxygen to the diene (716) in quantitative yield. Catalytic hydrogenation of 717 under pressure gave diol 718, from which water was eliminated, after basic hydrolysis of the urethane group, to give the indolenine 719. Lithium aluminum hydride reduction gave the indoline 720 which could be acetylated to deoxyaspidodispermine (158) under mild conditions (307) (Scheme 51). 

The carbonyl oxides prepared from the ozonolysis of enol ethers (for example, l-metoxy-4,8-dimethylnone-l,7 diene) undergo stereoselective intramolecular cycloaddition with inactivated alkenes yielding bicyclic di-oxalanes. The latter are easily converted into P-hydroxycarbonyl species and 1,3 diols by catalytic hydrogenation thus providing a new approach to the synthesis of 1,3-oxygenated products [80]. 

Isomerization of 1,3-diene epoxides. Noyori etalf have reported three types of isomerization of allylic oxides in the presence of a catalytic amount of this palladium(O) complex. One class, exemplified by the isomerization formulated in equation (I), involves transfer of a hydrogen atom from the Ca-alkyl group and results in a dienol of the type obtained in the ene reaction of singlet oxygen with 1,3-dienes. 

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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