Synthesis of 4-phenylselenyl-1H-pyrazoles by electrophilic cyclization

---

Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Edebiyat Fakültesi, Kimya Bölümü, Türkiye

Tezin Onay Tarihi: 2011

Öğrenci: DENİZ DEMİRCİ

Danışman: METİN ZORA

Özet:

In this study, the synthesis of 5-ferrocenyl/aryl-4-(phenylselenyl)-1H-pyrazole derivatives was investigated since the integration of ferrocenyl and selenium moieties into pyrazole derivatives may increase their current biological activities. Initially, the starting propargyl aldehydes were synthesized from corresponding acetylenes. Subsequently, propargyl aldehydes were reacted with hydrazines to yield corresponding hydrazones. Then the in situ synthesized hydrazones were subjected to electrophilic cyclization with phenylselenyl chloride, which afforded 5-ferrocenyl/aryl-4-(phenylselenyl)-1H-pyrazoles in one-pot manner. Subsequently, reaction conditions were optimized in terms of electrophile, base, temperature and solvent. Best results were obtained with phenylselenyl chloride and NaHCO3 at room temperature in DCM for ferrocenyl substituted pyrazoles and DCE for aryl substituted pyrazoles. In summary, by employing the electrophilic cyclizations of in situ synthesized acetylenic hydrazones, a variety of 5-ferrocenyl/aryl-4-(phenylselenyl)-1H-pyrazole derivatives were synthesized in one-pot way in moderate to good yields.