Oxidation of 1H-2-Benzoselenopyrans. Generation of Benzoselenophenes, Benzaldehydes, and Benzophenones
摘要:
Oxidation of 1H-2-benzoselenopyrans bearing electron-withdrawing substituents gave benzoselenophenes, benzaldehydes, and benzophenone derivatives via the corresponding selenoxides followed by Pummerer and [3,3]sigmatropic rearrangements.
Regioselective Synthesis of 1H-2-Benzoselenopyrans. Reaction of 4,4'-Dimethoxyselenobenzophenone with Acetylenes
摘要:
4,4'-Dimethoxyselenobenzophenone combines as a diene with methyl propiolate, ethyl propiolate, and phenylacetylene furnishing 1H-2-benzoselenopyrans; the primary [4+2] cycloaddition is followed by 1,3-proton shift. The reaction proceeds regioselectively. On the other hand, a nonaromatic ketone was obtained by using propiolic acid as a substrate.