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The reduction of cyclic and acyclic 1,2-diketones was investigated by employing whole cells of the yeast Rhodotorula minuta as biocatalyst. The reactions showed a variable degree of regio- and enantioselectivity depending on the nature of the substrate. In the case of cyclic diketones, the reduction afforded a mixture of diastereomeric diols only. The reduction of acyclic diketones allowed production of both the hydroxy ketone and the diol, in a two-step reaction. The first step was highly regio- and stereoselective, affording the hydroxy ketone of (S)-configuration with high enantiomeric excess. After longer reaction times the corresponding (S,S)-diols were obtained in high yield and diastereomeric excess.

A fast one-pot method has been developed for the direct preparation of 3-aryl-1,2-cyclohexanediones from 2,3-epoxycyclohexanone via a microwave-assisted tandem epoxy ketone isomerization-Heck arylation reaction. The preparative microwave-assisted reactions were performed preferentially in 50% aqueous poly(ethylene glycol) utilizing sodium acetate as the base. Within 5-30 min of directed microwave heating, employing less than 0.05 mol % of palladium acetate and no phosphine ligand, up to 72% yield of C3-arylated dike tones was isolated in an overall environmentally benign process. On the basis of the chemical reactivity of proposed intermediates, a reaction pathway is proposed where the acetate base promotes the rearrangement of the 2,3-epoxycyclohexanone into the active mono-enol form of 1,2-cyclohexanedione. An alternative classically heated procedure for isomerization-C3-arylation of 2,3-epoxycyclohexanone in DMF is also reported.

Oxidative cycloaddition of a 2-cyclohexenone or α-tetralone and an alkene with dried Mn(OAc)3 in benzene at 80-140 °C provides a general route to dihydrobenzofurans 15 and dihydronaphthofurans 17. Although the yields are modest, this one-pot reaction provides simple access to these compounds, which have previously been prepared by multistep routes. Oxidative cycloaddition of 2-cyclohexenones with β-methylstyrenes provides a new route to benzofuranoid neolignans, which was applied to the synthesis of conocarpan (22). The formation of 2-acetoxyhexanedioic acids 27 and 47 from acetoxylation of 2-cyclohexenones in HOAc, but not in benzene, opens up a new class of Mn(OAc)3 reactions and explains Watt and Demir's discovery that much higher yields of α'-acetoxy enones are obtained in benzene than in HOAc.

Benzeneselenenyl derivatives, PhSe-X (X=Cl, Br, OCOCH3, and SCN) react readily with α-diazo ketones, RCOC(N2)R1 (R1=H or alkyl), with loss of nitrogen, furnishing αα-adducts of the type RCOCR1(X)SePh.The α-chloro and α-bromo adducts can be converted into α-methoxy adducts in methanol-sodium hydrogen carbonate.The utility of these adducts in synthesis is illustrated by their conversion (where structural considerations permit) via selenoxide fragmentation into α-heterosubstituted αβ-unsaturated ketones.Treatment of the series RCOCR1(X)SePh (R1=alkyl; X=Cl, Br, OCOCH3, and OCH3) with hydrogen peroxide-pyridine produces α-chloro-, α-bromo-, α-acetoxy-, and α-methoxy-αβ-unsaturated ketones, whereas treatment of series RCOCR1(X)SePh (R1=alkyl; X=Cl and Br) with lithium carbonate in dimethylformamide produces α-phenylseleno-αβ-unsaturated ketones.Several α-substituted cyclopentenones, cyclohexenones, and cycloheptenones have been synthesised in this way and acyclic examples are illustrated by the synthesis of 3-chloro-, 3-bromo-, 3-acetoxy-, 3-methoxy,-and 3-phenylselenobut-3-en-2-one from 3-diazobutan-2-one.