Catalytic [2+2+1] Annulation of Elemental Sulfur and Diynes for Synthesis of Polythiophenes

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K15289
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 33020:Synthetic organic chemistry-related
• Research Institution: Tokyo Metropolitan University (2022); Tokyo University of Science (2020-2021)
• Principal Investigator: Ogiwara Yohei 東京都立大学, 理学研究科, 特任准教授 (00734394)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: チオフェン / 鉄触媒 / ジイン / 単体硫黄 / 環化

Outline of Final Research Achievements

Catalytic cyclization of elemental sulfur and diynes has been conducted for the construction of thiophene structures, which could be potentially applicable to a novel and effective synthetic method for polythiophenes. We initially prepared the starting diyne substrates from commercial reagents. Simple and general methods were applicable for the synthesis of diynes in one or two steps, we could obtain a variety of diynes with different steric and electronic properties in high yields. By using the diynes, [2+2+1] cycloadditions with elemental sulfur, S8, were next examined, and it was found that the thiophene formation reaction proceeded under several catalytic conditions. In particular, an iron complex showed good catalytic activity for the desired cyclization, the corresponding thiophene was formed in up to about 70% yield.

Free Research Field

有機合成化学

Academic Significance and Societal Importance of the Research Achievements

本成果によって、新しいチオフェン合成法の選択肢を有機合成化学分野に提供できた。反応効率や触媒安定性、基質適用範囲など、解決すべき課題は残されているものの、今後更なる最適化や触媒条件の調査によって、実利用可能なチオフェン合成法へと発展させていきたい。研究期間内には達成できなかったが、本手法は有機電子材料に含まれるポリチオフェン骨格の構築にも原理的には応用可能であるため、将来的には社会に還元できる合成手法になりうる基盤研究としての意義がある。