Electrophilic cyclization of (Z)-selenoenynes: synthesis and reactivity of 3-iodoselenophenes.
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.
Alves
Diego
D
Laboratório de Síntese, Reatividade, Avaliação Farmacológica e Toxicológica de Organocalcogênios, CCNE, UFSM, Santa Maria, Rio Grande do Sul, Brazil, 97105-900.
Luchese
Cristiane
C
Nogueira
Cristina W
CW
Zeni
Gilson
G
D000447:Aldehydes / Q000737:chemistry; D003500:Cyclization; D004583:Electrons; D007455:Iodine / Q000737:chemistry*; D008094:Lithium / Q000737:chemistry; D015394:Molecular Structure; D016566:Organoselenium Compounds / Q000138:chemical synthesis* / Q000737:chemistry
D000447:Aldehydes; D016566:Organoselenium Compounds; D007455:Iodine; D008094:Lithium