ChemInform Abstract: SYNTHESIS OF 6‐HYDROXYPYRROLOTETRAZOLES

Synthesis of 5-amino-4-hetaryl-2,3-dihydro-1h-3-pyrrolones

“…Signals for the proton at position 1 of the dihydropyrrolone ring and the protons of the amino group are observed in the 1 H NMR spectra of compounds 1a-h in the form of three one-proton singlets (one narrow and two broad) in the region of 7.5-8.5 ppm. The latter clearly belong to the protons of the amino group, which are magnetically nonequivalent as a result of the formation of an intramolecular hydrogen bond, as was observed earlier for analogous systems [28][29][30][31][32][33][34][35][36][37]. The protons of the heterocyclic substituent resonate in their characteristic regions.…”

“…Removal of the phthaloyl protection from the phthalimidonitriles 2a-h leads to the formation of the intermediates 5a-h, having the structures of γ-amino nitriles. According to data in [18][19][20][21][22][23][24][28][29][30][31][32][33][34][35][36][37], such aminonitriles undergo heterocyclization on account of intramolecular addition of the amino group to the nitrile group, which in this case should lead to the formation of the desired pyrrolones 1. In fact, the desired products 1a-h were obtained with yields of 40-60% by the action of a 3-4-fold excess of hydrazine hydrate on compounds 2a-h.…”

“…The principal methods for the synthesis of these compounds are the condensation of methylene-active nitriles with derivatives of α-aminocarbonyl compounds [12][13][14][15][16][17] or amination of substituted 4-halobutyronitriles [18][19][20][21][22][23][24] or their synthetic equivalents [25][26][27]. Both approaches have been successfully applied to the synthesis of 1-R 1 -2,2-R 2 ,R 3 -5-amino-4-hetaryl-2,3-dihydro-3-pyrrolones [28][29][30][31][32][33][34][35][36][37]. However, they cannot be used for the production of similar derivatives unsubstituted at position 1 since, on the one hand, the N-unsubstituted α-aminocarbonyl compounds quickly dimerize to pyrazine derivatives and, on the other, the use of ammonia in the reaction together with the need for heat and a nonaqueous medium give rise to certain technical difficulties.…”

New Method of Synthesis of 2-Amino-4(5H)-oxothiophenes

“…The synthesis of 2-amino-4(5H)-oxothiophenes with aryl and hetaryl substituents in position 3 of the molecule has not been developed in practice. Work of Japanese scientists is known [16], which describes 2-amino-(5H)-thiophen-4-ones with phenyl and 4-chlorophenyl substituents in position 3 of the molecule, displaying spasmolytic properties.Previously we synthesized 2-amino-4(5H)-oxothiophenes by the reaction of 4-chloro-2-hetaryl-3-oxobutyronitriles with sodium hydrosulfide [17]. The reaction proceeds through a stage of exchanging the chlorine atom for a sulfhydryl group with subsequent addition of this group to the triple bond of the nitrile group.…”

“…Previously we synthesized 2-amino-4(5H)-oxothiophenes by the reaction of 4-chloro-2-hetaryl-3-oxobutyronitriles with sodium hydrosulfide [17]. The reaction proceeds through a stage of exchanging the chlorine atom for a sulfhydryl group with subsequent addition of this group to the triple bond of the nitrile group.…”