Facile and Efficient Synthesis of Novel Oxazine, Oxazepine and Phenoxazine of Chromenones Fused with 1,4-Naphthoquinone

A series of novel mono ethers 5, 7, diethers 6, 8, 9, oxazine 10, oxazepine 11 and phenoxazines 12 of chromenones fused with 1,4naphthoquinone have been synthesized.[4] The clinical significance of these two class of compounds has stimulated the synthesis of novel ring systems agents retaining the core quinone and chromenone moiety.As part of our research program of the synthesis of biologically active quinones, 1 we became interested in the synthesis of novel oxazine, oxazepine, phenoxazine and ether derivatives of chromenones fused with 1,4-naphthoquinone.2,3-Dichloro-1,4-naphthoquinone 1 reacts readily with nucleophiles leading to substitution of one or both chlorine atoms. 5Based on the reactivity of 1, we have studied its reaction with chromenones 2-4 (one equivalents) in the presence of Na 2 CO 3 using DMSO as solvent at room temperature. 8Quinone 1 was reacted with 4-hydroxy-2H-chromen-2-one 2 to give a mixture of the 2-chloro-3-(2-oxo-2H-chromen-4yloxy)naphthalene-1,4-dione 5 and 2,3-bis(2-oxo-2H-chromen-4-yloxy)naphthalene-1,4-dione 6 in 72% and 11% yields respectively (Scheme 1) whereas reaction with 7-hydroxy-4-methyl-2H-chromen-2-one 3a and 7-hydroxy-2H-chromen-2-one 3b gave ethers, 2-chloro-3-(4-methyl-2-oxo-2H-chromen-7yloxy)naphthalene-1,4-dione 7a and 2-chloro-3-(2-oxo-2H-chromen-7-yloxy)naphthalene-1,4-dione 7b