Dearomative Migratory Rearrangement of 2-Oxypyridines Enabled by α-Imino Rhodium Carbene
作者:Guangyang Xu、Ying Shao、Shengbiao Tang、Qun Chen、Jiangtao Sun
DOI:10.1021/acs.orglett.0c03533
日期:2020.12.4
migratory rearrangement reactions of 2-oxypyridines with N-sulfonyl-1,2,3-triazoles have been developed under rhodium catalysis, providing a reliable and efficient protocol for accessing N-substituted 2-pyridones. These two distinct rearrangements feature the controllable 1,4-migration of a carbonate group from O-to-C as well as the O-to-N 1,6-migration of an acyl group via α-imino rhodium carbene transfer
The present invention relates to a novel method for producing diarylpyridine derivatives, and the object of the present invention is to provide a novel, industrially useful method. The present inventors developed a novel method for synthesizing pyridine rings without using palladium, a strong base, or a high-temperature reaction. In particular, they successfully developed a method that can be used to synthesize iminium salts as intermediates, synthesize cyano compounds from these iminium salts, and cyclize the cyano compounds into pyridines under very mild reaction conditions.
Utilizing acetyl hypofluorite for chlorination, bromination, and etherification of the pyridine system
作者:David Hebel、Shlomo Rozen
DOI:10.1021/jo00022a016
日期:1991.10
Acetyl hypofluorite, which is easily made from F2, possesses a strong electrophilic fluorine. This electrophile is able to attach itself to the nitrogen atom of pyridine and activate the ring toward nucleophilic attacks. The ultimate elimination of HF results in an overall easy nucleophilic displacement of the hydrogen of the important 2-position. The nucleophiles used; Cl-delta-, Br-delta-, and RO-delta-, originate from solvents such as CH2Cl2, CH2Br2, and various primary alcohols. Thus, 2-halo- or 2-alkoxypyridines were formed. The reaction conditions (room temperature, very short reaction times, and good yields) transform the task of direct substitution of the pyridine ring from an extremely difficult to a very easy procedure.
Oxygenation of the Unactivated Pyridine System by Acetyl Hypofluorite Made Directly from F2