Synthesis of naphtho[1,2-e]-pyrazolo[5,1-b][1,3]oxazines

Abstract

are of interest as intercalating and antibacterial agents [1][2][3] and also as photochromic materials [4,5]. However, the choice of suitable methods for preparing them is limited and includes thermolysis of imidoylketenes [6], condensation of thiophosgene with 2'-aminosalicylanilides [7], interaction of 2-azidomethylphenols with cyanogen bromide [8], and the reaction of tetrahydrocarbazoles with 2-chloromethylphenols [9]. OH R R NMe 2 O R N N Br R R 1 N H N Br R Br O R R N N Br R Br OH R R 1 1 DMF 1a-c 2a-e 2 2 1 2 -Me 2 NH -HBr 1a, 2a,d R = R 1 = H, 1b, 2b R = 1-Ad, R 1 = H, 1c, 2c,e R = H, R 1 = 4-MeOC 6 H 4 ; 2 a-c R 2 = Br, d,e R 2 = NO 2 We have shown that the new heterocyclic system of naphtho[1,2-e]pyrazolo[5,1-b][1,3]oxazines 2a-e are formed on the interaction of Mannich bases of the naphthalene series 1a-c with 3,4,5-tribromopyrazole or 3,5-dibromo-4-nitropyrazole in boiling DMF.

Conformational analysis of 3-methyltetrahydro-1,3-oxazine

“…The interest to non-symmetric 1,3-heterocyclic analogs of cyclohexane, especially to tetrahydro-1,3-oxazines is due to their peculiar structural features [1][2][3][4][5][6][7][8] and valuable pharmacological properties [9][10][11] as well as to their wide application in fine organic synthesis [6,[12][13][14][15][16][17][18][19] and developing of new polymeric materials [20,21]. Dipole moment measurements, NMR studies [1,22,23], and X-ray diffraction analysis [14] have led to conclusion that these compounds predominantly exist in the chair conformation with equatorial (C е ) or axial (C а ) orientation of the N-alkyl group.…”