Electrophilic Cyclization of (Z)-Selenoenynes: Synthesis and Reactivity of 3-Iodoselenophenes
摘要:
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.
Synthesis of 3-Alkynylselenophene Derivatives by a Copper-Free Sonogashira Cross-Coupling Reaction
作者:Diego Alves、Joel S. dos Reis、Cristiane Luchese、Cristina W. Nogueira、Gilson Zeni
DOI:10.1002/ejoc.200700707
日期:2008.1
3-Iodoselenophene derivatives undergo direct Sonogashiracross-couplingreactions with several terminal alkynes in the presence of a catalytic amount of Pd(PPh3)2Cl2 in DMF with Et3N as the base under cocatalyst-free conditions. This cross-couplingreaction proceeded cleanly under mild conditions and was performed with propargylic alcohols and propargylic ethers, as well as alkyl, vinyl and aryl alkynes
The Suzuki cross-coupling of 3-iodoselenophenes with boronicacids in the presence of catalytic amount of palladium salt is described. This cross-couplingreaction proceeded cleanly under mild conditions and was performed with aryl boronicacids bearing electron-withdrawing, electron-donating, and neutral substituents, furnishing the correspondents products in moderate to good yields.