Nicoletta Toniutti

New Heterocycles from the Reaction between Some Natural α-Amino Acid Hydrazides and Formaldehyde

The ring forming condensation between some natural α-amino acid phenylhydrazides (1) and aqueous formaldehyde (2) has opened a novel synthetic route to hexahydro-1,2,4-triazin-6-one derivatives (3). Polycyclic systems were obtained from the same reaction carried out with L-aspartic acid 1,4-bis(2-phenylhydrazide) (1d), L-histidine phenylhydrazide (1e) and L-tryptophan phenylhydrazide (1f) which gave perhydro-4,6-dioxo-2,8-diphenyl[1,2,4]triazino[4,5-d][1,2,4]triazepine (5) perhydro-1-oxo-3-phenylimidazo[5,4-d][1,2,4]triazino[4,5-a]pyridine (7) and 1,2,3-H-3-(2-phenylcarbazoyl)-β-carboline (8), respectively. Substrates 1 were conveniently obtained by direct reaction of phenylhydrazine with L-α-amino acid esters retaining the original chirality.

1-SUBSTITUTED 1,4,5,6-TETRAHYDROPYRIDAZINES AND 1-(N-SUBSTITUTED)-AMINOPYRROLIDINES FROM HYDRAZINES AND 2,5-DIMETHOXYTETRAHYDROFURAN

Abstract N-Substituted 1,4,5,6-tetrahydropyridazines ( 3 ) can be prepared in a one pot procedure from a hydrazine 1 and 2,5-dimethoxytetrahydrofuran ( 2 ) using NaBH4 in aqueous-THF acidic medium in fair yields. Variable amounts of two side products are also formed: hexahydropyridazines 5 , likely produced by a route other than the direct reduction of 3 , and 1-aminopyrrolidines 4 . A direct reduction-N-reductive ethylation of 3 could be achieved in AcOH with NaBH4.

REACTION OF NITROSOBENZENE WITH 4-METHOXY-N-METHYLENEANILINE

A 1:1 adduct produced in the reaction of nitrosobenzene (2) with 1,3,5-tris(4-methoxyphenyl)-1,3,5-triazinane (3) has been shown by X-ray diffraction structure analysis to be the N′-(4-methoxyphenyl)-N-phenyl-N-oxyformamidinium species 5.

New flavones by a novel synthetic route

Abstract Twelve new flavones ( 3 ) were prepared by the reaction of 2-hydroxy-α-bromoacetophenones ( 1 ) with piperidine or morpholine aminals of benzaldeydes ( 2 ) in refluxing methanol. The products ( 3 ) were fully characterised by 1 H NMR and IR spectroscopy and MS spectrometry.