Synthesis of Pyrazoles via Electrophilic Cyclization

ZORA M., KIVRAK A., YAZICI C.

JOURNAL OF ORGANIC CHEMISTRY, cilt.76, sa.16, ss.6726-6742, 2011 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 76 Sayı: 16
  • Basım Tarihi: 2011
  • Doi Numarası: 10.1021/jo201119e
  • Dergi Adı: JOURNAL OF ORGANIC CHEMISTRY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.6726-6742
  • Orta Doğu Teknik Üniversitesi Adresli: Evet

Özet

Electrophilic cyclizations of alpha,beta-alkynic hydrazones by molecular iodine were investigated for the synthesis of 4-iodopyrazoles. alpha,beta-Alkynic hydrazones were readily prepared by the reactions of hydrazines with propargyl aldehydes and ketones. When treated with molecular iodine in the presence of sodium bicarbonate, alpha,beta-alkynic hydrazones underwent electrophilic cyclization to afford 4-iodopyrazoles in good to high yields. Iodocyclization was general for a wide range of alpha,beta-alkynic hydrazones and tolerated the presence of aliphatic, aromatic, heteroaromatic, and ferrocenyl moieties with electron-withdrawing and electron-donating substituents.