Cu catalyzed [4 + 2] cycloaddition for the synthesis of highly substituted 3-fluoropyridines

Abstract

A copper catalyzed annulation-aromatization of benzyl trifluoromethyl ketimines with 3-acryloyloxazolidin-2-ones for the synthesis of 3-fluoropyridines through double C-F bond cleavages has been developed. In this approach, the annulation occurred between...

Transition‐Metal Catalyzed [4+2]‐Cycloaddition Reactions: A Sexennial Update

“…Considering the biological application of 3fluoropyridines, [139] various groups have synthesized 3-fluoropyridines by different methods. Fu [140] In this reaction, dienes were generated in situ from trifluoromethyl ketimines via first CÀ F bond cleavage, which react with unsaturated compounds followed by annula-Scheme 28. Copper catalyzed synthesis of 2H-pyrido[1,2-a]pyrimidines.…”

“…Copper catalyzed synthesis of 3-fluoropyridines. [140] Scheme 39. Copper catalyzed synthesis of 3-aryl-1,2,3,4tetrahydroisoquinolines.…”

“…in 2022 reported the synthesis of 3‐fluoropyridines 144 through double C−F bond cleavage from benzyl trifluoromethyl ketimines 142 and 3‐acryloyloxazolidin‐2‐ones 143 by copper‐catalyzed [4+2] annulations‐aromatization in good to moderate yields (Scheme 38). [140] In this reaction, dienes were generated in situ from trifluoromethyl ketimines via first C−F bond cleavage, which react with unsaturated compounds followed by annulation through second C−F bond cleavage to afford 3‐fluoropyridines. 144 can be further hydrolyzed to give multi‐substituted 3‐pyridine carboxylic acids.…”