Photoinduced Alkyl/Aryl Radical Cascade for the Synthesis of Quaternary CF3-Containing Oxindoles and Indoline Alkaloids.

Metal- and additive-free, photoinduced decarboxylative radical alkylation-cyclization of CF3-acrylamides with alkyl redox-active esters provided the corresponding quaternary CF3-oxindole derivatives in good yields. Notably, diaryliodonium salts also efficiently participated in the arylation-cyclization of CF3-acrylamides in environmentally benign H2O as a solvent. The present approach has been extended for the concise synthesis of CF3-attached indoline alkaloid analogues, i.e., CF3-(±)-desoxyeseroline, CF3-(±)-esermethole, and CF3-(±) progesterone receptor antagonists. The preliminary mechanistic studies revealed that the reaction is likely to proceed through initial photoexcitation of redox-active ester/diaryliodonium salts followed by the SET process with acrylamide.