The application of diazo oxime ethers in the synthesis of heterocycles

• Main Author: Qi, Xinxin
• Other Authors: School of Physical and Mathematical Sciences
• Format: Theses and Dissertations
• Language: English
• Published: 2013
• Subjects: DRNTU::Science::Chemistry::Organic chemistry::Organometallic compounds
• Online Access: http://hdl.handle.net/10356/54741
• Institution: Nanyang Technological University

In this thesis, we have investigated the reactivities of diazo oxime ethers and their applications in the synthesis of various heterocycles. As a result, 2-isoxazolines and 2H-azirines have been prepared from α-oximino diazo compounds with Rh2(Piv)4 under mild reaction conditions. Furthermore, 2H-azirines have been utilized in the one-pot reaction for pyrrole synthesis in the presence of 1,3-dicarbonyl compounds (Scheme 1). Free carbenes could also be generated from photolysis. Irradiation of α-diazo oxime ethers in benzene solution afforded 2-alkyl/aryloxy-2H-azirines through facile N–O bond insertion in good to excellent yields. This protocol allowed for a tandem reaction of pyrrole synthesis via 2-alkoxy-2H-azirines formation and 1,3-dipolar cycloaddition (Scheme 2). In our continued work on N–O bond insertion, a number of 3-hydroxypyridines have been prepared from δ-oximino diazo compounds catalyzed by Rh2(tfacam)4 (Scheme 3).