Mechanism of formation of trimethylisoxazole and intermediates upon alkaline hydrolysis of nitroethane

Abstract

Nitroethane and higher homologous primary nitroalkanes undergo a base-catalyzed condensation yielding the corresponding 2,3,4-trialkyisoxazoles. Basic hydrolysis of nitroethane to acetaldehyde is the key initial step followed by a series of condensation and elimination reactions. Through the use of appropriately 14C-labelled intermediates and acetaldehyde-d4, a relatively simple mechanism is indicated which will satisfactorily account for all observed intermediates indicated in a summary of the reaction sequence.

Reactions of tetranitromethane. Mechanism of the reaction of tetranitromethane with pseudo acids

“…Alternate pathways of decomposition of FHinvolving the steps kinetically equivalent to A4an(FH-), that is A4'(F), have been considered (Jewett, 1971) but will not be discussed here. Lockhart et al (1969) proposed that alkaline hydrolysis of nitroethane yields acetaldehyde and nitrite ion by way of addition of HOto the nitroethane anion (eq 20). A closer look at this reaction reveals that a two-electron oxidation is OH HO" I CH3CHNO2--> CH3CH-N(0-)2 ->-CH3CHO + H+ + required before nitrite ion could be formed.…”

Reduction of Some Alkylisoxazoles with Lithium Aluminum Hydride

“…We have previously described the mechanism of 3,4,5-trimethylisoxazole (1) formation from nitroethane as well as that for 3,4-dimethylisoxazole (2) using 14C-and 'H-labelled precursors (7). Among alternate methods considered for the location of label in the isoxazoles thus formed, lithium aluminum hydride reduction appeared as a viable procedure for the conversion of the heterocyclic compounds to the corresponding alicyclic 1,3-amino alcohols.…”