Carbon Atom Insertion into Pyrroles and Indoles Promoted by Chlorodiazirines
Balu D. Dherange, Patrick Q. Kelly, Jordan P. Liles, Matthew S. Sigman and Mark D. Levin*
*Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States, Email: marklevinuchicago.edu
B. D. Dherange, P. Q. Kelly, J. P. Liles, M. S. Sigman, M. D. Levin, J. Am. Chem. Soc., 2021, 143, 11337-11344.
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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.
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General Procedure for synthesis of 3-substituted quinolines and pyridines from indoles and pyrroles
To an oven dried 1-dram screw cap vial equipped with a stir bar and PTFE/white silicone septum was added indole/pyrrole (0.2 mmol) and dry CH3CN (1 mL), followed by diazirine (0.6 mmol) and Na2CO3 (0.6 mmol). The vial then sealed with electric tape. The mixture was then allowed to stir at 50 °C for 12 h and then allowed to cool to 25 °C. The reaction mixture was quenched by the addition of saturated aqueous NH4Cl solution (1mL), and the two phases were separated. The aqueous layer was extracted with EtOAc (3×3mL), and the combined organic layers were dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure. The obtained residue was purified by flash column chromatography to afford 3-substituted quinoline/pyridine.