Abstract
Author(s): D. Ramesh1*, MN. Kumaraswamy1 and KM. Nagarsha
The key starting material, 2-hydroxy-1-naphtholdoxime 1 was synthesized from naphtholdehyde and converted to ethyl -3-aminonaphtho[2,1-b]furan-2-carboxylate 2. Similarly the reaction 1 with phenacyl bromide in the presence of anhydrous potassium carbonate in dimethyl formamide afforded 2-benzoyl-3-aminonaphtho[2,1-b]furan 6 by a known method. In this case condensation and Thorpe-Ziegler cyclization occurred in a single step. 2-Benzoyl-3-aminonaphtho[2,1-b]furan 6 on treatment with chloroacetyl chloride give corresponding a chloroacetamido compound 7 which on bromination and Nitration gave N-(2- benzoyl-8-substitutednaphtho[2,1-b]furan-1-yl)-2-chloroacetamide 8a-b. The compounds 8a-b underwent cyclization in methanolic ammonia to produce 5-phenyl-1H-2,3-dihydro-(8-substituted naphtho[2,1-b]furo[3,2-e])-1,4-diazepine-2-one 9a-b. Another method for the formation of 1,4-diazepine ring has been devised. In this method ethyl-3- aminonaphtho[2,1-b]furan-2-carboxylate 2 was converted into corresponding chloroacetyl compound 3 which on bromination and Nitration gaveethyl 1-[(chloroacetyl)amino]-8 substitutednaphtho[2,1-b]furan-2-carboxylate 4a-b. The compounds 4a-b underwent cyclization in methanolic ammonia to produce 1H-2,3,4,5-tetrahydro-(8-substitutednaphtho[2,1-b]furo[3,2- e])-1,4-diazepine-2,5-dione 5a-b. The condensation of 6 with ethyl chloroformate in the presence of anhydrous potassium carbonate in absolute ethanol to afford 2-benzoyl-3-carbethoxyaminonaphtho[2,1-b]furan 10. The compounds 10 on bromination and nitration yields 2-benzoyl-3-carbethoxyamino-8- substitutednaphtho[2,1-b]furan11a-b. The compound 11a-b was further reacted with derivatives of hydrazine in refluxing ethanol. The products formed were identified as the hydrazones12a-d. The cyclization of hydrazones12a-d was brought about by refluxing these compounds with acetic acid to obtain 5-phenyl-3-substituted-1H-2,3-dihydro-8-substituted naphtho[2,1-b]furo[3,2-e]- 1,3,4-trizapin-2-ones 13a-d. The structures of the compounds are confirmed on the basis of IR, 1H NMR spectral data. The compounds 5a-b 9a-b, 13a-d are screened for Antibacterial and Antifungal activities