Direct photo-induced reductive Heck cyclization of indoles for the efficient preparation of polycyclic indolinyl compounds† † Electronic supplementary information (ESI) available: Experimental details, photophysical data, DFT calculations and NMR spectral data. CCDC 2101130 and 2101131. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/d1sc04258k

ABSTRACT: The photo-induced cleavage of C(sp2)–Cl bonds is an appealing synthetic tool in organic synthesis, but usually requires the use of high UV light, photocatalysts and/or photosensitizers. Herein is described a direct photo-induced chloroarene activation with UVA/blue LEDs that can be used in the reductive Heck cyclization of indoles and without the use of a photocatalyst or photosensitizer. The indole compounds examined display room-temperature phosphorescence. The photochemical reaction tolerates a panel of functional groups including esters, alcohols, amides, cyano and alkenes (27 examples, 50–88% yields), and can be used to prepare polycyclic compounds and perform the functionalization of natural product analogues in moderate to good yields. Mechanistic experiments, including time-resolved absorption spectroscopy, are supportive of photo-induced electron transfer between the indole substrate and DIPEA, with the formation of radical intermediates in the photo-induced dearomatization reaction. Metal- and photocatalyst-free reductive Heck cyclization of indoles under light irradiation was developed and used to prepare polycyclic compounds and functionalize natural product analogues in moderate to good yields.

SUBMITTER: Yu D 

PROVIDER: S-EPMC8565399 | biostudies-literature |

REPOSITORIES: biostudies-literature