Studies on chalcogen-containing heterocycles. Part 37: m-CPBA oxidation of isotellurochromenes and isoselenochromenes
摘要:
The oxidation of the 1-unsubstituted isotellurochromenes and isoselenochromenes with m-CPBA resulted in a novel ring-opening reaction to give the o-formyl distyryl ditellurides and diselenides as the sole products in good yields, respectively. The o-benzoyl distyryl ditelluride and diselenide were also produced from the corresponding 1-phenylisochromenes. In contrast, the 1-benzyl and 1-n-butylisochromenes were oxidized to afford the (Z)-1-benzylideneisochromenes and (Z)-1-butylideneisochromenes under similar conditions; no distyryl compounds were obtained. The distyryl compounds were also obtained by the hydrolysis of the corresponding 2-benzochalcogenopyrylium salts, which were easily converted from the 2-benzoisochromenes by treatment with triphenylcarbenium tetrafluoroborate (Ph3C+BF4-). (C) 2012 Elsevier Ltd. All rights reserved.
Reaction of 2-Benzotelluropyrylium Salts with Organocopper Reagents: Introduction of a Carbon Functional Group at the C-1 Position of the Telluropyrylium Cation Ring
作者:Haruki Sashida、Hirohito Satoh、Kazuo Ohyanagi
DOI:10.3987/com-03-9944
日期:——
3-tert-Butyl-2-benzotelluropyrylium salt (13A) react with lithium dialkyl(phenyl)copper to give in good yield the corresponding isotellurochromenes (15A) having a carbon functional group at the C-1 position. Similarly, the 1-substituted isoselenochromenes (15B) and the 4-substituted tellurochromene (19) were also prepared from the corresponding pyrylium salts (13B, 18). The obtained isotellurochromenes (15A) were easily converted into the corresponding 2,4-disubstituted 2-benzotelluropyrylium salts (20) by the treatment with triphenylcarbenium tetrafluoroborate (Ph3C+ BF4-).