The oxidation of 1-unsubstituted or 1-phenyl-1H-isotellurochromenes with m-chloroperbenzoic acid (mCPBA) in CHCl3 resulted in a ring opening reaction to produce as the sole products the corresponding o-formyl or benzoyl distyryl ditellurides, which were also produced by the hydrolysis of the 2-benzotelluropyrylium salts readily prepared from the parent isotellurochromene.
1-unsubstituted or 1-phenyl-1H-isotellurochromenes with m-chloroperbenzoic acid (mCPBA) in CHCl3 的氧化反应导致开环反应,生成的唯一产物是相应的邻甲酰基或苯甲酰基二丙烯基二碲化物。
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
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.