Regioselective Diastereomeric Michael Adducts as Building Blocks in Heterocyclic Synthesis.

The reaction of 4-(4-acetylamino/bromophenyl)-4-oxobut-2-enoic acids with carbon nucleophiles afforded Michael adducts depending on the type of reagents and medium (acidic or basic). The adducts 2 and 3 were used as key starting materials to synthesize some heterocyclic compounds, which include pyridazinone, furanone, 1,2-oxazin-5-one, 1.2-diazapine, pyrane, and hydroxyl pyridine derivatives. The Steric factor plays an important role in regioselectivity. The structure of newly synthesized compounds was elucidated by elemental analysis and spectroscopic data. [ABSTRACT FROM AUTHOR]