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Stereocontrolled convergent synthesis of vitamin A was achieved by the double elimination method employing the C10 sulfone and the C10 aldehydes as starting materials. Thus the all-trans and 13-cis isomers were obtained with the stereochemical purity of 95% and 90%, respectively.

The ethynylation of ketone (2) in liquid ammonia at −33°C with stoichiometric sodium acetylide afforded the corresponding alcohol (3 and 4). Similar treatment of 1 resulted in only a little isomerization to 2. Favorskii ethynylation under pressure at 0°C yielded a mixture of 1, 2, 3 and 4 without any detectable 5, whichever ketone 1 or 2 being used.

Oxy-Cope rearrangement of diastereomeric l,5-hexadien-3-ols, new key intermediates for terpenoids pio-duction in industrial scale, were investigated in neat systems and solvent assisted systems. Various solvents affecting the selectivity of [3,3]-shift were classified by means of NMR studies on hydroxyl proton exchange time.

Double bond migration of 2,5-dienones 3 to 2,4-dienones 2 (e.g. pseudoionone) was effectively carried out by using nickel acetylacetonate catalyst in N-methyl-2-pyrrolidone solvent.

Tertiary amine N-oxides were found to be effective for converting allylic chlorides to α,β-unsaturated aldehydes.

Coupling reaction of 6-cupro-2,3-dimethoxy-5-methylhydroquinone bis(2-methoxyethoxymethyl) ether with (2E)-1-(phenylsulfonyl)-2-methyl-4-chloro-2-butene afforded the sulfone-functionalized prenylhydro quinone (6) in 82% yield. Stereoselective synthesis of ubiquinone-10 was achieved by the condensation of 6 and solanesyl bromide (yield 92%), reductive elimination of the sulfone group by sodium–ethyl alcohol in THF (yield 80%), and followed by air oxidation of the hydroquinone.

4-Hydroxyindole (1a), a useful intermediate for Pindolol (1b), has been prepared via electrooxidative coupling of 1,3-cyclohexadione with ethyl vinyl ether followed by ammonolysis and dehydrogenation.