66416-43-1Relevant articles and documents
Carbon Atom Insertion into Pyrroles and Indoles Promoted by Chlorodiazirines
Dherange, Balu D.,Kelly, Patrick Q.,Levin, Mark D.,Liles, Jordan P.,Sigman, Matthew S.
, p. 11337 - 11344 (2021/08/16)
Herein, we report a reaction that selectively generates 3-arylpyridine and quinoline motifs by inserting aryl carbynyl cation equivalents into pyrrole and indole cores, respectively. By employing α-chlorodiazirines as thermal precursors to the corresponding chlorocarbenes, the traditional haloform-based protocol central to the parent Ciamician-Dennstedt rearrangement can be modified to directly afford 3-(hetero)arylpyridines and quinolines. Chlorodiazirines are conveniently prepared in a single step by oxidation of commercially available amidinium salts. Selectivity as a function of pyrrole substitution pattern was examined, and a predictive model based on steric effects is put forward, with DFT calculations supporting a selectivity-determining cyclopropanation step. Computations surprisingly indicate that the stereochemistry of cyclopropanation is of little consequence to the subsequent electrocyclic ring opening that forges the pyridine core, due to a compensatory homoaromatic stabilization that counterbalances orbital-controlled torquoselectivity effects. The utility of this skeletal transform is further demonstrated through the preparation of quinolinophanes and the skeletal editing of pharmaceutically relevant pyrroles.
Oxidative alkylation of alkenes with carbonyl compounds through concomitant 1,2-aryl migration by photoredox catalysis
Lin, Zhaowei,Lu, Maojian,Liu, Boyi,Gao, Jing,Huang, Mingqiang,Gan, Zhenhong,Cai, Shunyou
, p. 16031 - 16035 (2020/10/08)
Visible-light-enabled oxidative radical 1,2-alkylarylation of α-aryl allylic alcohols with carbonyl compounds has been established under mild conditions. An efficient and convenient protocol for the construction of a variety of 1,5-dicarbonyl compounds wa
Regioselective Pd-Catalyzed Synthesis of 2,3,6-Trisubstituted Pyridines from Isoxazolinones
Rieckhoff, Stefan,Hellmuth, Tina,Peters, René
supporting information, p. 6822 - 6830 (2015/10/05)
Substituted pyridines are prevalent heterocycles of fundamental importance. Their efficient regioselective preparation is often still a challenge despite a large number of reported synthetic methodologies. In this letter we report an operationally simple approach that makes use of readily accessible isoxazolinones. The protocol involves a Pd(II)-catalyzed C-regioselective 1,4-addition to vinylketones, followed by a Pd(0)-catalyzed transformation, which is assumed to proceed via vinylnitrene-Pd intermediates. Both hydrogen and air are necessary for the pyridine formation step and could be employed at ratios above the upper explosive limit thus avoiding a safety issue. This new strategy allows an effective, scalable and practical access to various previously unknown 2,3,6-trisubstituted pyridines.
