Heterocyclic compound studies. II. Synthesis of 1,4-benzodioxin, 1,4-benzoxathiin, 1,4-benzoxazine and 1,4-benzothiazine derivatives

Abstract Benzocondensed six‐membered heterocyclic rings containing two heteroatoms have been synthesized by a generally applicable method starting from disubstituted benzene compounds and methyl 4‐chlorobutynoate ( 1 ) or methyl 4‐bromobutenoate ( 2 ). The reactions with 1 yield a mixture of endo and exo ( E or Z) isomers. The 13 C nmr spectroscopy was used to assign the structure of the synthesized compounds.