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The enantiomerically pure cis-1,2-dihydrocatechols 2, which are generated by enzymatic dihydroxylation of the corresponding aromatic, engage in regio- and stereo-controlled Diels-Alder cycloaddition reactions to give a range of synthetically useful bicyclo[2.2.2]octenes. Certain examples of the latter type of compound have been used as starting materials in the synthesis of the sesquiterpenoids (−)-patchoulenone and (−)-hirsutene.

The enantiomerically pure cis-1,2-dihydrocatechol 3, which is obtained in quantity by microbial dihydroxylation of toluene, has been converted over ten steps, including an initial Diels–Alder cycloaddition reaction, into the tricyclic ketone 12. Direct irradiation of a benzene solution of the latter compound affords a mixture of compounds 13 and 14 which embody the tricyclic frameworks of the sesquiterpene natural products tsugicoline A (1) and isovelleral (2), respectively.

cis-1,2-Dihydrocatechols 5 (X= Me and Cl), which are available in homochiral form through the whole-cell biotransformation of toluene and chlorobenzene, respectively, undergo Diels-Alder cycloaddition reactions with a range of electron-deficient dienophiles at 19 kbar (1.9 GPa). The favored products of such reactions are adducts of the general form 8 and that arise through the operation of a contrasteric or syn-addition pathway. In contrast, the acetonide derivatives of metabolites 5 undergo anti-selective addition reactions under the same conditions and so producing adducts of the general form 10. Bicyclo[2.2.2]octenes 8 and 10, which embody carbocyclic frameworks of opposite enantiomeric form, are useful scaffolds for chemical synthesis.Computational studies reveal that syn-adduct formation is kinetically and normally thermodynamically favored over anti-adduct formation when the free diols 5 are involved but the reverse is so when the corresponding acetonides participate as the 4π-addend. Furthermore, the reactions become more exothermic as pressure increases while, concurrently, the activation barrier diminishes and at 6 GPa (60 kbar) almost vanishes.

The cis-1,2-dihydrocatechol (2), which is obtained in enantiopure form by microbial oxidation of chlorobenzene, has been converted, via 3,5-O-benzylidene-L-gulono-1,4-lactone (8), into L-ascorbic acid (1).

The preparation and characterisation of monomeric and linked metal carbonyl clusters containing the closo-Si 2 Co 4 pseudo-octahedral core. Cameron