Iron nitrosyl complexes and their applications in organic catalysis

• Main Author: Wang, Yang
• Other Authors: Tan Choon Hong
• Format: Theses and Dissertations
• Language: English
• Published: 2018
• Subjects: DRNTU::Science::Chemistry
• Online Access: http://hdl.handle.net/10356/73930
• Institution: Nanyang Technological University

Chemists have described Iron-sulfur cluster nitrosyls complexes over 100 years ago. Since the role of nitric oxide in various physiological processes was discovered in the 1980s, the investigation of transition metal nitrosyl complexes has become very important. In this study, we would like to contribute some perspectives towards iron-nitrosyl complex from organic catalysis aspect. We present a mild method for regioselective allylic sulfenylation of vinyl ethylene carbonate using [Bu4N]2[Fe2(SR)2(NO)4]. This active species can be prepared in situ starting from the readily available Fe2(SR)2(NO)4, potassium hydride, and Bu4NBr. This protocol allows for the coupling of a broad substrate range. Electron-poor and -rich aromatic, as well as some aliphatic ones, can be used in the presence of 5 mol% iron-complex to form a new C-S bond with good regioselectivity, and the protocol features good Z-selectivity at room temperature. Furthermore, we tested this method in enantioselective desymmetrization of meso vinyl carbonate substrate by introducing the concept of chiral ion pairing catalysis. Inspired by the initial results in asymmetric catalysis, we find a new strategy to produce chiral allenes through asymmetric decarboxylative isomerization of cyclic alkynal carbonates catalyzed by an iron nitrosyl-chiral bisguanidinium ion pairs. This is the first example of asymmetric allene formation catalyzed by an iron catalyst without any chiral ligands.