SYNTHESIS AND MOSQUITO REPELLENT PROPERTIES OF 2,2-DIALKYL-N-ACETYLOXAZOLIDINES AND 2-ALKYL-4,4-DIMETHYL-N-ACETYLOXAZOLIDINES

Nineteen novel N-acetyl-2,2-dialkyloxazolidines (2) and N-acetyl-2-alk yl-4,4-dimethyloxazolidines (3) were synthesized from commercially ava ilable carbonyl compounds and ethanolamine or 2-amino-2-methyl-1-propa nol. Their bioactivity against laboratory-reared mosquitoes was compar ed in patch tests to known N-acetyl-2-alkyloxazolidines (1) and N,N-di ethyl-m-toluamide (deet insect repellent). Isomeric composition measur ements by [C-13]NMR spectroscopy favoured the Z rotational isomer for samples of 2 (91-96% Z) and the E rotational isomer for samples of 3 ( 66-71% E), in agreement with molecular mechanics calculations on rotat ional isomers of model oxazolidines. Samples of 1 were previously show n to exist in solution mostly as the Z isomer (60-70% Z). Within the o ptimal molecular weight range for these experimental chemicals, the du ration of repellency against Aedes aegypti (L.), Anopheles quadrimacul atus Say and Anopheles albimanus Wiedemann generally followed the orde r: 1 > 2 > deet > 3. Bioassay data are discussed in relation to the eq uilibrium populations of rotational isomers for substituted N-acetylox azolidines.