Photoinduced Alkyl/Aryl Radical Cascade for the Synthesis of Quaternary CF<sub>3</sub>-Containing Oxindoles and Indoline Alkaloids
Ranjay Shaw, Naveen Sihag, Swati Jain, Ruchi Sharma, M. Ramu Yadav
Abstract
Metal- and additive-free, photoinduced decarboxylative radical alkylation–cyclization of CF 3 -acrylamides with alkyl redox-active esters provided the corresponding quaternary CF 3 -oxindole derivatives in good yields. Notably, diaryliodonium salts also efficiently participated in the arylation–cyclization of CF 3 -acrylamides in environmentally benign H 2 O as a solvent. The present approach has been extended for the concise synthesis of CF 3 -attached indoline alkaloid analogues, i.e., CF 3 -(±)-desoxyeseroline, CF 3 -(±)-esermethole, and CF 3 -(±) 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.