Juvenile hormones (JHs) play key roles in regulating metamorphosis and reproduction in insects. The last two steps of JH synthesis diverge depending on the insect order. In Lepidoptera, epoxidation by a P450 monooxygenase precedes esterification by a juvenile hormone acid methyltransferase (JHAMT). In Orthoptera, Dictyoptera, Coleoptera and Diptera epoxidation follows methylation. The aim of ou...

Ambient formaldehyde concentrations are reported from the North Atlantic Marine Boundary Layer Experiment (NAMBLEX) campaign at Mace Head on the west coast of Eire during August 2002. The results from two techniques, using direct determination via gas chromatography and the Hantzsch technique, show similar trends but a significant off set in concentrations. For westerly air flows characteristic...

A new synthetic approach to polyfunctional hexahydropyrrolo[3,4-b]pyrroles was developed based on cyclization of N-arylbromomaleimides with aminocrotonic acid esters. A highly chemo- and stereoselective reaction is a Hantzsch-type domino process, involving the steps of initial nucleophilic C-addition or substitution and subsequent intramolecular nucleophilic addition without recyclyzation of im...

The biochemistry of the violaxanthin cycle in relationship to photosynthesis is reviewed. The cycle is a component of the thylakoid and consists of a reaction sequence in which violaxanthin is converted to zeaxanthin (de—epoxidation) and then regenerated (epoxidation) through separate reaction mechanisms. The arrangement of the cycle in the thyla— koid is transmembranous with the de—epoxidation...

Thiophene containing thiazolyl carbohydrazide on reaction with various aryl isothiocynates yields thiosemicarbazides which were transformed into 1,2,4- substituted thiazoles by Hantzsch synthesis and characterized spectral methods. Most of the synthesized new are found to be promisingly effective against tested bacterial strains exhibited moderate activitytested fungal strains. 1, 2,4- weakly a...

effects of imidazoles and substituted pyridines and pure s-donors on the oxidation of cyclooctene with naio4 by 5,10,15,20-tetraphenylporphyrinato-manganese(iii) acetate, mn(tpp)oac, and 5,10,15,20-tetramesitylporphyrinato-manganese(iii) acetate, mn(tmp)oac, catalysts in ch2cl2-h2o solvent are studied. coordination of the nitrogen donors to the mn-catalysts generally caused a reduction in the e...

some 3, 5-diacyl or 3,5-diester 1,4-dihydropyridines were oxidized to the corresponding pyridine derivatives using hydrogen peroxide in aqueous ethanol in the presence of potassium bromide and acetic acid as the catalysts. the reaction was carried out in ethanol and products were isolated in high to excellent yields. however, oxidation of 3,5-diacetyl 1,4-dihydropyridines is slower than 3,5-die...