Butane-2,3-dione oximate

Kinetic studies of the reaction between the a-nucleophile, butane-2-3-dione oximate (Ox ), and p-nitrophenyl thionobenzoate (18) in DMSO-H2O mixtures of varying compositions at 298,308, and 318 K revealed that, based on a comparison of rates of reaction with a normal nucleophile, p-chlorophenoxide, the a-effect showed a bell-shaped profile, the maximum value occurring at 50% DMSO at all temperatures, but decreasing as the temperature increased. Dissection of the activation parameters, A7/ and revealed that the bell-shaped a-effect behaviour is due to entropy of activation differences rather than enthalpy terms, although the enthalpy term controls almost entirely the solvent-dependent dramatic increase in reaction rate (about 2000-fold greater in 80% DMSO than in H2O). Differences in the TS structures for the reactions with Ox ... 

Similar to enol esters, oximes can also be used as irreversible acyl transfer agents for lipase catalysis. Thus, instead of a di-enol ester, Athavale et al. [67] polymerized diols with bis(2,3-butane dione monoxime) alkanedioate using Lipozyme IM-20. The results obtained by activation with enol-esters and their corresponding oximes were comparable. No attempts were made to analyze the end-group of the polyester. 

Individually indexed compounds are f Acetaldehyde oxime, 0865 Acetone oxime, 1258 Azoformaldoxime, 0815 Benzaldehyde oxime, 2760 Bromoacetone oxime, 1201 Butane-2,3-dione dioxime, 1595... 

The Rh(I)/dppf complex-catalysed 2-i-2-i-2-cycloaddition of oximes and diynes formed substituted pyridines in moderate to good yields (88%), under mild conditions. A one-pot procedure has been developed using aldehydes.The Ni-catalysed 2 -I-2 -I-2-cycloaddition of isocyanates (117) with 1,3-dienes (118) in MeCN produced 6-substituted dihydropyrimidine 2,4-diones (119). A key intermediate in this reaction is a five-membered azanickelacyclic species (Scheme 35). " The enantioselective cationic Rh(I)-catalysed 2-i-2-i-2-cycloaddition of diynes and isocyanates formed axially chiral pyridones with high ees (82%). The unique source of chirality is provided by a system containing [Rh(cod)Cl]2, l,4-bis(diphenylphosphino)butane, and the silver phosphate salt Ag(5)-TRIP. " " The Rh-catalysed 2-I-2-I-2-cycloaddition of diynes to sulfonimines in DCE, at r.t. to 80 °C, yielded 1,2-dihydropyridines in good yields (54-86%) and enantioselectivity (61-96%... 

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