摘要:

N N S R N NPh 5 N N N N 8 O R Ph N N H S NNHPh O R 4A N N H N N S COR Ph N N 4B H NPh N S H COR 6A ii R O Br NNHPh 1 S N R NNHPh 2A N S R H 3 N NPh S HN R 2B N NPh N N SMe NNHPh R 6B N N 7 N N Ph R i SMe H N S R NHPh 11 N S R NHPh 10 iii N NAr N N S RCO Ph 9 1 v iv vi NPh N N RCO C6H4Me- p Ph a Ar = Ph b Ar = 4-MeC6H4 c Ar = 4-ClC6H4 10 H O O R = 350 J. CHEM. RESEARCH (S) 1997 J. Chem. Research (S) 1997 350–351 J. Chem. Research (M) 1997 2244–2254 Reactions with Hydrazonoyl Halides. Part 16.1 A Convenient Synthesis of 1,4-Benzothiazine Triazolo[4,3-a]- benzimidazole Thiazolo[3,2-a]benzimidazole and 2,3-Dihydro-1,3,4-thiadiazole Derivatives Nabil M. Hassan and Abdou O. Abdelhamid* Department of Chemistry Faculty of Science Cairo University Giza Egypt A synthesis of 1,4-benzothiazines triazolo[4,3-a]benzimidazole thiazoles and 2,3-dihydro-1,3,4-thiadiazoles has been accomplished from the reaction of hydrazonoyl bromide 1 with 2-aminobenzenethiol benzimidazole-2-thiol 2-methylsulfanylbenzimidazole dithiocarbamate and dithiocarbazate.Hydrazonoyl halides are versatile reagents which have been extensively utilized in the synthesis of numerous heterocycles. 2–7 Here we report the results of our study of the reaction of 2-aminobenzenethiol benzimidazole-2-thiol 2-methylsulfanylbenzimidazole dithiocarbamates phenyl thiourea and dithiocarbazate with the hydrazonoyl bromide 1. Treatment of 1-bromo-2-(4-cyano-5-phenyl-1-p-tolylpyrazol- 3-yl)ethanedione 1-phenylhydrazone (1) with 2-aminobenzenethiol in ethanol in the presence of triethylamine gave one isolable product whose mass spectral data and elemental *To receive any correspondence.Scheme 1 Reagents i 2-aminobenzenethiol; ii benzimidazole-2-thiol; iii 2-methylsulfanylbenzimidazole; iv methyl N-phenyldithiocarbamate; v phenylthiourea; vi arenediazonium chloride R1 R2 NNHC(S)SR3 1 + O R S N N R1 R2 SR3 NNHPh 13 O R N N S Ph SR3 NHN R1 R2 14 O R N N S Ph NN R1 R2 15 N N S NHN 19 O R N N S Ph NHNH2 17 1 + NH2CSNHNH2 a R = H R2 = 4-MeC6H4 b R = H R2 = 2-C4H3S c R = H R2 = 3-C4H3O d R = H R2 = 3-C5H4N e R = H R2 = 4-C5H4N f R = Me R2 = Ph g R = Me R2 = MeC6H4 h R = Me R2 = 4-ClC6H4 i R = Me R2 = 2-C4H3S 12-15 R N NPh N S NHNH2 18 R N NPh CHC6H4Me- p N N C6H4Me- p NC Ph R = 12a-f 16a R3 = Me R3 = Et J. CHEM. RESEARCH (S) 1997 351 analysis indicated a molecular formula C31H22N6S. The product may possess either the structure 2A or its tautomeric azo structure 2B or 3.The product 3-(4-cyano-5-phenyl- 1 - p- tolylpyrazol - 3 - yl) - 2 - phenylhydrazono - 2H- 1,4 - benzothia - zine (2A) seems to be the predominant form on the basis of spectral data (IR 1H NMR mass and UV). The hydrazonoyl bromide 1 reacts readily with benzimidazole- 2-thiol in ethanolic sodium ethoxide solution to yield a product identified as 1-(4-cyano-5-phenyl-1-p-tolylpyrazol- 3-yl)-2-phenylazothiazolo[3,2-a]benzimidazole (5) or 1-(4- c y a n o - 5 - p h e n y l - 1 - p- t o l y l p y r a z o l - 3 - y l c a r b o n y l ) - 3 - p h e n y l - 3H-[1,2,4]triazolo[4,3-a]benzimidazole (8) (Scheme 1). Structure 8 resulted via elimination of hydrogen sulfide from the corresponding intermediate 6A formed from the 1,3-dipolar cycloaddition of nitrile imide (generated in situ from 1 and triethylamine) to the C�N double bond of the imidazole ring.The structure of 5 is explained by a stepwise path involving substitution to give a cyclic hydrazone 4A. Cyclization of the latter is completed by elimination of one molecule of water. The structure 5 was derived from elemental analysis and spectral data. On the other hand the hydrazonoyl bromide 1 reacts with 2-methylsulfanylbenzimidazole in ethanol in the presence of triethylamine to afford 8. This product 8 resulted via the thermal elimination of methanethiol from the corresponding cycloadduct 7 formed from a cyclic hydrazone 6B. The structure of the product 8 was inferred from elemental analysis and spectral data. Also the hydrazonoyl bromide 1 reacts with methyl Nphenyl dithiocarbamates in ethanolic triethylamine to give 2,3-dihydro-2-phenylimino-1,3,4-thiadiazole derivatives 9.The structure of the products was confirmed on the basis of elemental analysis and spectral data. On the other hand the reaction of 1 with N-phenylthiourea in ethanolic triethylamine afforded the 2-anilino-5-phenylazothiazole derivative 10a. The structure of 10 was elucidated on the basis of elemental analysis spectral data and comparison with an authentic sample (prepared by the reaction of benzenediazonium chloride with 2-anilinothiazole 11 in ethanolic sodium acetate) (Scheme 1). The hydrazonoyl bromide 1 reacts readily with methyl (or ethyl) dithiocarbazate 12 or 16 in ethanolic triethylamine at room temperature to afford the 2,3-dihydro-1,3,4-thiadiazoles 15 (Scheme 2).The structures of the products were derived from elemental analyses and spectral data. The products 15 are assumed to be formed via elimination of methanethiol (or ethanethiol) from the corresponding 14 formed from the 1,3-cycloaddition of nitrile imide to the C�S double bond of methyl (or ethyl) dithiocarbazate. The formation of 14 can also be explained by a stepwise path involving substitution to afford the cyclic hydrazone 13 which was readily cyclized to give the intermediate 14 which subsequently eliminates alkanethiol to give the final products 15 (Scheme 2). We tried to obtain the thiadiazoles 15 by an alternative route by the reaction of 1 with thiosemicarbazide in ethanolic triethylamine. The 2-hydrazinothiazole 18 was obtained. The structure of 18 was established on the basis of elemental analysis and spectral data.Product 18 readily reacts with p-tolualdehyde in ethanol to give the corresponding hydrazone 19. From the above data the structure 17 cannot be obtained through the reaction of 1 and thiosemicarbazide. Techniques used IR 1H NMR UV and mass spectrometry References 12 Tables 1 and 2 Data for 9 and 15a–i Received 26th February 1997; Accepted 2nd June 1997 Paper E/7/01359K References cited in this synopsis 1 Part 15 H. A. Emam H. F. Zohdi and A. O. Abdelhamid J. Chem. Res. in the press. 2 A. O. Abdelhamid J. Chem. Res. 1993 (S) 208; (M) 1239. 3 A. O. Abdelhamid F. A. Khalifa F. A. Attaby and F. H. H. El-Shiaty Phosphorus Sulfur Relat. Elem. 1992 72 135. 4 A. S. Shawali Chem. Rev. 1993 93 2731. 5 A. Padwa Angew. Chem. Int. Ed. Engl. 1976 15 123. 6 R. Huisen R. S. Ustman and G. Wallbillich Chem. Ber. 1976 100 1787 7 A. O. Abdelhamid F. F. Abd-El-Mageid N. M. Hassan and H. F. Zohdi J. Chem. Res. 1995 (S) 492; (M) 3036. Sche

ISSN:0308-2342    

DOI:10.1039/a701359k

出版商:RSC    

年代:1997

数据来源: RSC