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Research has been conducted on the second-order rate constants. These constants have been measured for the addition of amines to ketenes in acetonitrile solution via the laser flash photolysis technique.

Flash photolysis of 10-diazo-9(10H)-phenanthrenone in aqueous solution provided two successively formed transient species, producing fluorene-9-carboxylic acid. The transients were identified as fluorenylideneketene, produced from a photo-Wolff reaction. Bromine scavenging determined the rate of enolization of fluorene-0-carboxylic acid.

A study of isomerization rate profiles of 1H-indene-1-carboxylic acid to 1H-indene-3-carboxylic acid in dilute aqueous solutions reveals an enolization-reketonization reaction sequence. 1-carboxylic acid and 3-carboxylic acid have carbon acid acidity and keto-enol equilibrium constants of 9.35 and 11.69, and 7.26 and 9.6, respectively. The study uses H2PO4, (CH3)(3)CPO3H and HCO3 anions as buffers.

Flash photolytic production of phenylcyanoketene by a photo-Wolff reaction of alpha-cyano-alpha-diazoacetophenone after hydration of the ketene provided the enol of alpha-cyano-alpha-phenylatic acid as a short-lined transient species. Estimations of the rates of ketonisation of the enol in dilute hydrochloric acid solutions, acetic acid, biphosphate ion, tris(hydroxymethyl)methylamine and ammonia buffers provided a rate profile with turning points. The first and second acid ionization constants of the enol could be establish from this profile.

Kinetic studies of acid dissociation of N-(pentafluorophenyl)-2-phenylethynamine in aqueous solution reveal that the reaction has a pK(a) value of 10.28 and the acidifying effect is evaluated as 10 pK units. Flash photolysis of an aminocyclopropenone produces this ynamine and it undergoes isomerization to ketenimine in aqueous solutions. Kinetic isotopic studies help examine the isomerization reaction and determine rate constants for various steps.

Describes the flash photolysis of five diazonaphthoquinones in aqueous solution. Production of ketene and carboxylic enol intermediates preceding the ultimate indenecarboxylic acid reaction products; Catalysis of the decay of the two intermediates.

Tertiary amines react rapidly and reversibly with arylketenes in acetonitrile forming observable zwitterions, and these undergo amine catalyzed dealkylation forming N,N-disubstituted amides. Reactions of N-methyldialkylamines show a strong preference for methyl group loss by displacement, as predicted by computational studies. Loss of ethyl groups in reactions with triethylamine also occur by displacement, but preferential loss of isopropyl groups in the phenylketene reaction with diisopropylethylamine evidently involves elimination. Quinuclidine rapidly forms long-lived zwitterions with arylketenes, providing a model for catalysis by cinchona and related alkaloids in stereoselective additions to ketenes.

Four generations of chemoenzymatic approaches to oseltamivir are presented. The first two generations relied on the use of cyclohexadiene-cis-diol derived enzymatically from bromobenzene. The third and fourth generation used the corresponding diol obtained from ethyl benzoate by fermentation with E. coli JM109(pDTG601a). Oseltamivir was obtained from ethyl benzoate by intersecting intermediate 39 (third-generation synthesis) and intermediate 45 (fourth-generation synthesis). Both of these advanced approaches benefited from symmetry considerations and translocation of the acrylate double bond with concomitant elimination of the C-1 hydroxyl. The syntheses are evaluated for overall efficiency by the use of efficiency metrics and compared with other syntheses of oseltamivir (both academic and industrial).