Condensed Isoquinolines. 10. Borohydride Reduction in the 5H-Isoquino[2,3-a]quinazolin-5-one Series

Borohydride reduction in a series of 7-benzyl- and newly synthesized 7-arylmethylene-7,12-dihydro-5H-isoquino[2,3-a]quinazolin-5-ones leads stereoselectively to erythro-7-benzyl-6,6a,7,12-tetrahydro-5H-isoquino[2,3-a]quinazolin-5-ones. 7,7-Disubstituted 7,12-dihydro-5H-isoquino[2,3-a]quinazolin-5-ones are inert to the action of sodium borohydride, but spiro[5H-isoquino[2,3-a]quinazolin-7(12H),2'-indane]-5-one is reduced under rigid conditions to 6,6a-dihydrospiro[5H-isoquino[2,3-a]quinazolin-7(12H),2'-indan]-5-one. 7-Acetyl- and 7-benzoyl-6,11-dihydro-5H-isoquino[2,3-a]quinazolin-5-ones are converted in an aqueous alcoholic solution of sodium borohydride to the previously described 6,6a,7,12-tetrahydro-5H-isoquino[2,3-a]quinazolin-5-one. The structure and special features of the conformational behavior of the reduction products obtained were demonstrated by ¹H NMR spectroscopy.!     

Condensed isoquinolines 29. Oxidation reactions of 5-aryl-7,12-dihydroisoquino[2,3-a]quinazolinium salts

5-Aryl-7,12-dihydroisoquino[2,3-a]quinazolinium perchlorates are readily oxidized by atmospheric oxygen to form the products of oxidative coupling 5,5′-bis(aryl)-3,3′-dihalo[7,7′]bi[isoquino-[2,3-a]quinazoline-13,13′-diylium perchlorates. Heating 3-chloro-5-phenyl-7,12-dihydroisoquino-[2,3-a]quinazolinium perchlorate in nitrobenzene gives the 3-chloro-5-phenylisoquino[2,3-a]quinazolin-13-ium perchlorate. The aromatic 5-arylisoquino[2,3-a]quinazoline derivatives obtained react with nucleophilic reagents to form addition products at the C-12 atom. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 428–439, March, 2008.     

Condensed isoquinolines. 20. Characteristic features of thermal rearrangement of 7,12-dihydro-5H-isoquino[2,3-a]quinazolin-5-one to form 6,11-dihydro-13H-isoquino[3,2-b]quinazolin-13-one

We studied the dependence of the direction of conversions for salts of angular 7,12-dihydro-5H-isoquino[2,3-a]quinazolin-5-one on temperature and the nature of the anion: heating in high-boiling solvents leads either to aromatization of the heterosystem or to the rearrangement product, the linear 6,11-dihydro-13H-isoquino[3,2-b]quinazolin-13-one. When its hydrobromide is heated in high-boiling solvents, along with dimerization of the linear isomers, processes of oxidation at the positions 6 and 11 of the heterosystem occur. The dimer obtained in the reaction with morpholine is readily cleaved, with formation of a 6-(4-morpholyl)-substituted linear compound. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 430–439, March, 2007.     

Condensed Isoquinolines. 15. Synthesis of 5,10-Dihydro[1,2,4]triazolo[1,5-b]isoquinolines and Related Spiranes

Condensation of o-bromomethylphenylacetonitrile with arylcarbohydrazides gave, depending on the reaction conditions, 2-arylcarboxamido-1,4-dihydroisoquinoline-3(2H)-imine hydrobromides or 2-aryl-5,10-dihydro[1,2,4]triazolo[1,5-b]isoquinolines. Analogous condensation of 4-(2-bromomethylphenyl)tetrahydro-2H-pyran-4-carbonitrile and 1-(2-bromomethylphenyl)-1-cyclopentanecarbonitrile with arylcarbohydrazides gave respectively 2-aryl-2,3,5,6-tetrahydrospiro[4H-pyran-4,10'(5'H)-[1,2,4]triazolo[1,5-b]isoquinolines and 2-arylspiro[1,2,4]triazolo[1,5,b]isoquinoline-10(5'H)-1'-cyclopentanes, derivatives of new spirane heterocycles. The reaction with condensing agents of 3-imino-2,2',3,3'5',6'-hexahydrospiro[isoquinoline-4(1H),4'-4H-pyran]-2-amine and 3-imino-2,3-dihydrospiro[isoquinoline-4(1H),1'-cyclopentane]-2-amine hydrobromides, synthesized from the corresponding bromo nitriles and hydrazine, may serve as an alternative route for the synthesis of these compounds. The structure of obtained triazoloisoquinolines was established from IR, ¹H and ¹³C NMR spectra. An X-ray crystallographic study of 2-phenylspiro[1,2,4]triazolo[1,5-b]isoquinoline-10(5H),1'-cyclopentane was carried out.     

Condensed isoquinolines. Part 6. Synthesis of 5-aryl-7,12-dihydroisoquino[2,3-a]quinazolinium salts

2-(o-Aroyl)phenyl-1, 4-dihydroisoquinolin-3(2H)-imine hydrobromides have been synthesized by the reaction of o-bromomethylphenylacetonitrile with o-aminobenzophenones. The products were cyclized into 5-aryl-7,12-dihydroisoquino[2,3-a]quinazolinium perhclorates.T. G. Shevchenko University, Kiev 252017. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 664–666, May, 1995. Original article submitted April 15, 1995.     

Condensed isoquinolines 31. Reaction of 5-aryl-3-halo-12H-isoquino[2,3-a]quinazolines with electrophilic reagents

Treatment of 5-aryl-3-halo-12H-isoquino[2,3-a]quinazolines with electrophilic reagents readily forms their oxidation products. Acylation of the 3-chloro-5-phenyl-7,12-dihydroisoquino[2,3-a]quinazolinium perchlorate with Ac₂O in the presence of pyridine gave the product of electrophilic substitution at the C-7 atom 1-(3-chloro-5-phenyl-12H-isoquino[2,3-a]quinazolin-7-yl)-1-ethanone. By the same route phenacyl bromides react with the anhydro base 1 to give 5-aryl-7-(2-aryl-2-oxoethyl)-3-halo-isoquino[2,3-a]quinazolin-13-ium bromides. These salts readily react with nucleophilic reagents to form the products of addition at the C-12 atom. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1044–1052, July, 2008.     

Synthesis of 2,3-dihydro-5H-oxazolo[2,3-B]quinazolin-5-ones

Iodide-catalyzed ring expansion of 2-[(1-aziridinylcarbonyl)amino]benzoic acid methyl ester (2) gave 2,3-dihydro-5H-oxazolo[2,3-b]quinazolin-5-one (3) in quantitative yield. Treatment of the dimethyl analog of 2 (9) with sodium iodide in acetone gave a mixture of the 2,3-dihydro-2,2-dimethyl- (10) and 2,3-dihydro-3,3-dimethyl-5H-oxazolo[2,3-b]quinazolin-5-ones (11). However, rearrangement of 9 with sulfuric acid produced only 10. Synthesis of 11 by another route for comparison is described, and the known syntheses of 2,3-dihydro-5H-oxazolo[2,3-b]quinazolin-5-ones are reviewed.     

Condensed isoquinolines 25. Alkylation of 6,11-dihydro-13H-isoquino[3,2-<Emphasis Type="Italic">b</Emphasis>]quinazolin-13-one

Interaction of 6,11-dihydro-13H-isoquino[2,3-b]quinazolin-13-one with alkylating agents occurs at two positions depending on their nature and the reaction conditions-at C₍₆₎ or N₍₅₎. Fusion with methyl tosylate leads to 5-methyl-13-oxo-6,13-dihydro-11H-isoquino[3,2-b]quinazolin-5-ium salts, while interaction with benzyl halides in the presence of i-PrONa gave 6-benzyl-and 6,6-dibenzyl-6,11-dihydro-13H-isoquino[3,2-b]quinazolin-13-ones. Alkylation with olefins led to two types of products. In the case of maleinimides and maleic acid anhydride Michael adducts at C₍₆₎ were formed and in the case of cyanocinnamic acid esters the reaction was accompanied by intramolecular acylation at N₍₅₎ to give 1-aryl-3,9-dioxo-3H,9H,11H-benzo[5,6][1,8]naphthyridino[1,8-ab]quinazoline-2-carbonitrile. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No.11, 1698–1708, November 2007.     

Synthesis of 5H-benzothiazolo[3,2-a]quinazolin-5-ones

5H-Benzothiazolo[3,2-a]quinazolin-5-ones (Va-d) were synthesized by thermal cyclization of N-(2-benzothiazolyl)-2-fluorobenzamides (IVa-d) which were obtained by allowing 2-fluorobenzoyl chloride to react with 2-aminobenzothiazoles.     

Synthesis of 5H-benzoxazolo[3,2-a]quinazolin-5-ones

5H-Benzoxazolo[3,2-a]quinazolin-5-ones (Xa-d) were synthesized in excellent yields from N-(2-hydroxyphenyl)anthranilic acids (Ia-d) and cyanogen bromide. The synthesis was based on the mechanistic consideration of the reactions of salicylic acid with cyanogen bromide previously reported in the literature. A versatile alternative route to these novel heterocyclic compounds was through thermal cyclization of N-(2-benzoxazolyl)-2-fluorobenzamides (XIII) obtained by reacting 2-fluorobenzoyl chloride with 2-aminobenzoxazoles. The reaction of Xb with ethanol in the presence of potassium hydroxide gave an ethoxyquinazolinone (XVII). Similarly, the alkaline hydrolysis of Xb afforded an quinazolindione (XVIII).     

Synthesis of 2,3-dihydro-10bh-oxazolo[2,3-a]isoquinolines from ortho-lithiated phenyloxazolinyloxiranes

A general method for the synthesis of 2,3-dihydro-10bH-oxazolo[2,3-a]isoquinolines from the reaction of (R*,R*)-configured ortho-bromophenyloxazolinyloxiranes and organolithiums is described.     

Microwave assisted synthesis of 2,3-dihydro-4H-benzo[4,5]thiazolo[3,2-a]furo[2,3-d]pyrimidin-4-ones and 6,7-dihydro-5H-furo[2,3-d]thiazolo[3,2-a]pyrimidin-5-ones using Mn(OAc)3

2-Hydroxy-4H-benzo[4,5]thiazolo[3,2-a]pyrimidin-4-one 2a and 7-hydroxy-5H-thiazolo[3,2-a]pyrimidin-5-one 2b, were obtained in high yields under mild conditions from the cyclization reactions of bis-(2,4,6-trichlorophenyl) malonate and 2-aminobenzothiazole or 2-aminothiazole, respectively. A new class of compounds, 2,3-dihydro-4H-benzo[4,5]thiazolo[3,2-a]furo[2,3-d]pyrimidin-4-ones and 6,7-dihydro-5H-furo[2,3-d]thiazolo[3,2-a]pyrimidin-5-ones, were synthesized via the microwave assisted radical addition of compounds 2a and 2b to various alkenes using manganese(III) acetate. A preliminary acetylcholine esterase (AchE) inhibition test of compound 4e showed excellent (92%) inhibitory potential, comparable with the standard drug Donapezil®.     

Some chemical properties of 2,3-dihydro-4H-[1,3]thiazino[3,2-a]benzimidazol-4-one and 2-aryl-2,3-dihydro-4H-[1,3]thiazino[3,2-a]benzimidazol-4-ones

We have studied the reaction of 2,3-dihydro-4H-[1,3]thiazino[3,2-a]benzimidazol-4-one and 2-aryl-2,3-dihydro-4H-[1,3]thiazino[3,2-a]benzimidazol-4-ones with amines, alkylating reagents, and hydrogen peroxide. We have shown that the presence of an aryl substituent at the 2 position of [1,3-thiazino[3,2-a]benzimidazol-4-ones has a substantial effect on the direction of the reactions. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 445–452, March, 2006.     

Reactions of 2,3-Dioxopyrrolo[2,1-a]isoquinolines with Ammonia and Aliphatic Amines

2,3-Dioxopyrrolo[2,1-a]isoquinolines, with either a tertiary amide substituent at position 1 or no substituent, react with ammonia and aliphatic amines with ring opening to form the corresponding enamino keto amides.     

Condensed isoquinolines. 19. Synthesis of 1′-R-spiro[6a,11b-diazabenz[e]aceanthrylene-6(7H),4′ (1′H)-pyridine]-5,7(12H)-diones

During acylation of 7-isonicotinoyl-6,12-dihydro-5H-isoquino[2,3-a]quinazolin-5-one or its alkylation followed by treatment with organic bases, spirocyclization occurs with formation of derivatives of a novel heterocyclic system: 1′-acyl-and 1′-alkylspiro[7H,12H-6a,11b-diazabenz[e]aceanthrylene-6(5H),4′(1′ H)-pyridine]-5,7-diones. We have studied the spectral properties of the synthesized spirans. We have shown that 7-nicotinoyl-6,12-dihydro-5H-isoquino[2,3-a]quinazolin-5-one does not undergo an analogous reaction of repeated acylation, while treatment of its quaternary salt with bases leads to a complex mixture of unidentified products. For Communication 18, see [1]. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 113–122, January, 2006.     

A new one-step synthesis of 2,3-dihydro-5H-thiazolo[2,3-b]quinazolin-5-one and 3,4-dihydro-2h,6h[1,3]thiazino[2,3-b] quinazolin-6-one

2,3-Dihydro-5H-thiazolo[2,3-b]quinazolin-5-one and 3,4-dihydro-2H,6H[1,3] thiazino[2,3-b]-quinazolin-6-one have been synthesized in one step by the reaction of methyl anthranilate with ehloroalkyl isothiocyanates.