The chemistry of N-substituted 3-amino-1H-2-benzopyran-1-ones and 5-amino-2,3-dihydrofuran-2-ones. Ene-type reactions involving transfer of acyl groups. X-Ray crystal structure of cis-3,4-dihydro-4-morpholinocarbonyl-3-p-nitrophenyl-1H-2-benzopyran-1-one

Abstract

The (secondary amino)-1H-2-benzopyran-1-ones (1) add numerous aromatic aldehydes to yield geometrically isomeric lactones (7) in a manner that constitutes an ene reaction in which an acyl group is transferred. Analogous dihydrobenzopyranones (14) and (15) were obtained from cyclohexanone and diphenylketen. Addition to imines gave dihydroisoquinolones (16) and (17), phenyl isocyanate yielded the tetrahydroisoquinolinedione (18), and nitrosobenzene and carbon disulphide afforded the adducts (19) and (25), respectively. The morpholinobenzopyran-1-one (1a) added to the azo-group of 4-phenyl-1,2,4-triazoline-3,5-dione to yield compound (20); a similar reaction with arenediazonium salts resulted in the phthalazinone derivatives (23). Addition to dimethyl acetylenedicarboxylate produced the naphthol (26); trans-β-nitrostyrene afforded a mixture of two geometrically isomeric tetralones (27) and (28) with retained configuration. The unisolable morpholinobutenolide (30a) was intercepted by reaction with aromatic aldehydes and with dimethyl acetylenedicarboxylate to yield the adducts cis- and trans-(31), and (32), respectively. N-t-Butylsuccinisoimide reacts as the enamine tautomer (30b) with p-nitrobenzaldehyde, forming the γ-lactones (31d). X-Ray diffraction of the cis-isomer of 3,4-dihydro-4-morpholinocarbonyl-3-p-nitrophenyl-1H-2-benzopyran-1-one (7a) shows that the p-nitrophenyl group is equatorial and the morpholinocarbonyl substituent axial.