We present here our results of the electrophilic cyclization reaction of (Z)-chalcogenoenynes using butyltellurium tribromide as an electrophilic source. The cyclization reaction proceeded cleanly under mild reaction conditions and 3-(butyltellanyl)chalcogenophenes were formed in moderate to excellent yields. Subsequent, using these heterocycles as substrate to palladium-catalyzed cross-coupling reactions a new carbon-carbon bond was formed in good yields.
Electrophilic Cyclization of (<i>Z</i>)-Selenoenynes: Synthesis and Reactivity of 3-Iodoselenophenes
作者:Diego Alves、Cristiane Luchese、Cristina W. Nogueira、Gilson Zeni
DOI:10.1021/jo070835t
日期:2007.8.31
We present here our results of the electrophilic cyclization reaction of (Z)-selenoenynes with different electrophiles such as I-2, ICl, PhSeBr, and PhSeCl. The cyclization reaction proceeded cleanly under mild reaction conditions, and 3-substituted selenophenes were formed in moderate to excellent yields. We observed that the nature of solvent and structure of (Z)-selenoenyne were important to the cyclization reaction. In addition, the obtained 3-iodoselenophenes were readily transformed to more complex products using a metal-halogen exchange reaction with n-BuLi and trapping the intermediate formed with aldehydes, furnishing the desired secondary alcohols in good yields. Conversely, using the palladium or copper catalyzed cross-coupling reactions with terminal alkynes or alkyl alcohols, we were able to convert 3-iodoselenophene to Sonogashira or Ullmann type products, respectively, in good yields.
Selective base-promoted synthesis of substituted selenophenes by carbocyclization of (Z)-benzylselenoenynes
作者:Daniela A. Barancelli、Carmine I. Acker、Paulo H. Menezes、Gilson Zeni
DOI:10.1039/c0ob00844c
日期:——
We herein described the synthesis of several 3-benzyl-2,5-diarylselenophene derivatives in moderate to good yields using (Z)-benzylselenoenynes as starting material in carbocyclization reactions. The reactions were carried out under mild conditions using only t-BuOK as base, in the complete absence of transition metals or additives. The cyclized 3-benzyl-2,5-diarylselenophenes obtained in the current protocol appear highly promising and attractive intermediates for the synthesis of polysubstituted selenophenes. For instance, 3-benzyl-2,5-diphenylselenophene was treated with Br2 provided the corresponding 3-benzyl-4-bromo-2,5-diphenylselenophene in high yield. 4-Bromoselenophene derivative was applied as substrate in the palladium catalyzed cross-coupling reactions with boronic acids to give the Suzuki type products in excellent yields.
Green synthesis of halogenated thiophenes, selenophenes and benzo[b]selenophenes using sodium halides as a source of electrophilic halogens
作者:Tanay Kesharwani、Krystal A. Giraudy、Jordan L. Morgan、Cory Kornman、Abayomi D. Olaitan
DOI:10.1016/j.tetlet.2017.01.007
日期:2017.2
Herein, we report the first synthesis of chlorinated benzo[b]selenophenes via environmentally friendly electrophilic chlorocyclization reaction using "table salt" as a source of "electrophilic chlorine" and ethanol as a solvent. In addition, the synthesis of diverse halogenated heterocycles, including 3-chloro, 3-bromo and 3-iodo thiophenes, selenophenes, and benzo[b]selenophenes was successfully accomplished