Ph3P(O)-mediated electrochemical dearomative reduction of indole derivatives has been established, providing a straightforward and sustainable approach to hydrogenated and deuterated indolines. The protocol eliminates the need for an external reductant under mild conditions, achieving selective reduction of the pyrroline moiety in moderate to good yields with satisfactory D-incorporation. Mechanistic studies reveal the involvement of an electrochemically generated indolyl radical anion as a key intermediate. The protocol is readily scalable to the gram scale, underscoring its practicality and potential utility in synthetic and isotopic labeling applications.
Zhu et al. (Mon,) studied this question.