Diastereoselective Synthesis of Dihydroquinolin-4-ones by a Borane-Catalyzed Redox-Neutral endo-1,7-Hydride Shift
Garrit Wicker, Roland Schoch and Jan Paradies*
*Paderborn University, Chemistry Department, Warburger-Strasse 100, D-33098 Paderborn, Germany,
Email: jan.paradies
uni-paderborn.de
G. Wicker, R. Schoch, J. Paradies, Org. Lett., 2021, 23, 3626-3630.
DOI: 10.1021/acs.orglett.1c01018
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Abstract
Amino-substituted chalcones undergo a 1,7-hydride shift upon Lewis acid activation to form a zwitterionic iminium enolate, which collapses to dihydroquinoline-4-ones in high yields with an excellent diastereoselectivity.
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General procedure
The substrate (250 μmol, 1.00 equiv.) and B(C6F5)3 (2.6 mg, 25.0 μmol, 0.100 equiv.) were dissolved in CHCl3 (0.1 M) and placed in a crimp seal glass vial. The reaction mixture was stirred at room temperature or 60 °C for 18h. The resulting mixture was diluted with 10 ml DCM, washed with 10 ml H2O, and extracted twice with 10 ml DCM. The combined organic layers were dried over Na2SO4 and volatiles were removed under reduced pressure. Subsequent flash chromatography (mixtures of CH/EA, SiO2) yielded the desired compound.
Key Words
ID: J54-Y2021
