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Synthesis of [2‐aryl‐6‐oxo‐6 H ‐chromeno[6,7‐ d ]oxazol‐8‐yl]‐acetic acid ethyl esters
Author(s) -
Čačić Milan,
Trkovnik Mladen,
Čačić Frane,
HasSchön Elizabeta
Publication year - 2006
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570430204
Subject(s) - chemistry , acetic acid , ethanol , organic chemistry , aldehyde , ethyl acetate , alcohol , catalysis
AbstractA number of coumarino[6,7‐ d ]oxazoles (nitrogen analogs of psoralens) have been synthesized from (7‐hydroxy‐2‐oxo‐2 H ‐chromen‐4‐yl) acetic acid ethyl ester 1 . The synthetic route began with the nitration of 1 with nitric acid in acetic acid to give (6‐nitro‐7‐hydroxy‐2‐oxo‐2 H ‐chromen‐4‐yl) acetic acid ethyl ester 2 ; (3,6‐dinitro‐7‐hydroxy‐2‐oxo‐2 H ‐chromen‐4‐yl) acetic acid ethyl ester 3 and (3,6,8‐trinitro‐7‐hydroxy‐2‐oxo‐2 H ‐chromen‐4‐yl) acetic acid ethyl ester 4 . The reduction of 2 was accomplished with tin(II) chloride, tin, and concentrated hydrochloric acid in ethanol giving (6‐amino‐7‐hydroxy‐2‐oxo‐2 H ‐chromen‐4‐yl) acetic acid ethyl ester 5 . After the condensation of aminocoumarin 5 with aromatic aldehyde in glacial acetic acid medium, followed the dehydrocyclization to coumarino[6,7‐ d ]oxazoles 7a‐k . The intermediate Schiff's bases 6a‐k have been obtained from 5 with aromatic aldehyde in ethanol. Antibacterial and antifungal activities of the compounds have been evaluated.