Reaction of 2-Benzoselenopyrylium Salts with Nucleophiles: Formation of 1-Functionalized Isoselenochromenes
摘要:
1-Unsubstituted isoselenochromenes (3) were converted into the 2-benzoselenopyrylium salts (4) by treatment with Ph3C+BF4- and the reaction of the salts (4) with several nucleophilic reagents (alcohol, amine, cyanide, acetone, and Grignard reagents) afforded the corresponding 1-functionalized isoselenochromenes (5-9) in high yields, respectively. 1-Alkyl- and 1-phenyl-2-benzoselenopyrylium salts (10) were also obtained from 9.
Studies on Tellurium-Containing Heterocycles. Part 20. Reactions of 2-Benzoselenopyrylium Salts and 2-Benzotelluropyrylium Salts with Nucleophiles: Formation of 1-Functionalized 1H-Isoselenochromenes and 1H-Isotellurochromenes
作者:Haruki Sashida、Kazuo Ohyanagi
DOI:10.1248/cpb.52.57
日期:——
were produced by the reaction of the salts 1 with Grignard reagents, were converted to the corresponding 1,3-disubstituted 2-benzopyrylium salts (14-17, 19) by treatment with triphenylcarbenium tetrafluoroborate (Ph(3)C(+) BF(4)(-)), respectively. The 1-benzylselenopyrylium salts (19A) and 1-benzyltelluropyrylium salts (19B) exist in the solvent as an equilibrium mixture of the salts (19) and the corresponding
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.
Studies on tellurium-containing heterocycles. Part 18.1 Preparation and structure of 2-benzotelluropyrylium salts and 2-benzoselenopyrylium salts
The regioselective and stereospecific intramolecular ring closure reactions of o-ethynylbenzyl tellurols 5A and o-ethynylbenzyl selenols 5B, which were readily generated by the reaction of the o-ethynylbenzyl bromides 4 with sodium hydrogen telluride (NaHTe) or sodium hydrogen selenide (NaHSe), produced the isotellurochromenes 6A and isoselenochromenes 6B together with (Z)-1-methylidene-2-telluraindans
Reaction of 2-Benzoselenopyrylium Salts with Nucleophiles: Formation of 1-Functionalized Isoselenochromenes
作者:Haruki Sashida、Kazuo Ohyanagi
DOI:10.3987/com-98-8384
日期:——
1-Unsubstituted isoselenochromenes (3) were converted into the 2-benzoselenopyrylium salts (4) by treatment with Ph3C+BF4- and the reaction of the salts (4) with several nucleophilic reagents (alcohol, amine, cyanide, acetone, and Grignard reagents) afforded the corresponding 1-functionalized isoselenochromenes (5-9) in high yields, respectively. 1-Alkyl- and 1-phenyl-2-benzoselenopyrylium salts (10) were also obtained from 9.