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.
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
Studies on tellurium-containing heterocycles. Part 10.1 2-Benzotelluropyrylium salts: first preparation and reactions with Grignard reagents
作者:Haruki Sashida、Kazuo Ohyanagi
DOI:10.1039/a804036b
日期:——
The first simple preparation of 2-benzotelluropyrylium salts 4 from o-ethynylbenzyl bromides 1 in two steps, and the characteristic reaction of these salts 4 with benzylmagnesium bromide and other Grignard reagents are described.
to afford the (Z)-1-methylidene-2-phenyl-1,3-dihydro-1H-benzo[c]selenophenium salts as the majorproducts during the 5-exo-dig mode cyclization in good yields together with minor E isomers. The structure of the major (Z)-selenophenium salt was established by the single crystal X-ray crystallographic analysis using a tert-butyl derivative.
邻乙炔基苄基苯基硒化物与三氟甲磺酸区域选择性反应,生成(Z)-1-亚甲基-2-苯基-1,3-二氢-1 H-苯并[ c ]硒代苯酚盐,为5-exo-期间的主要产物dig模式环化以及少量的E异构体,收率很高。通过使用叔丁基衍生物的单晶X射线晶体学分析确定了主要的(Z)-硒烯鎓盐的结构。