Synthesis of N-(3,4,10,10a-Tetrahydro-2H-1,9-dioxa-4a-azaphenanthrene-6-yl)alkyl and Aryl Sulfonamides

摘要

Commercially available 2-amino-4-nitrophenol (1) was treated with chloroacetyl chloride to obtain 6-nitro-4H-benzo[1,4]oxazine-3,2-one (2). The latter was reacted with ethyl 3-bromopropionate to obtain 3-(6-nitro-3-oxo-2,3-dihydrobenzo[1,4]oxazine-4-yl)propionic acid ethyl ester (3), which on treatment with lithium aluminiumhydride gave 6-nitro-3,4,10,10a-tetrahydro-2H-1,9-dioxo-4a-azaphenanthrene (4) by reductive cyclization. Compound, 4 was treated with H2/Pd-C containing di-tert~butyldicarbonate (Boc)2O in THF to obtain the (3,4,10,10a-tetrahydro-2H-1,9-dioxa-4a-azaphenanthrene-6-yl)carbamie acid tert-butyl ester (5). The latter, on treatment with alkyl or arylsulfonyl chlorides in the presence of NaH gave N-(3,4,10,10a-tetrahydro-2H-1,9-dioxa-4a-azaphenanthrene-6-yl) alkyl or aryl sulfonamide-N~1-carbamic acid tert-butyl ester (6). N-Boc group of 6 was de-protected with Cs2CO3/imidazole in acetonitrile to give the title compounds N-(3,4,10,10a-tetrahydro-2H-1,9-dioxa-4a-azaphenanthrene-6-yl) alkyl or aryl sulfonamides (7) as potential antibacterial agents. All the new products obtained in the above sequences of reactions have been adequately characterized by spectral data.