Photochemical Synthesis of Succinic Ester-Containing Phenanthridines from Diazo Compounds as 1,4-Dicarbonyl Precursors

We disclosed herein a straightforward photochemical method for the construction of phenanthridines containing a synthetically useful succinate unit. The reaction occurred under visible-light irradiation with cheap eosin Y Na as photoredox catalyst and a diazo compound as the succinate precursor. Under the optimal reaction conditions, a wide range of phenanthridines were obtained in moderate to good yields. Note that the succinate units in the final heterocycles could be easily transformed into many valuable structures, such as gamma-butyrolactone, dihydrofuran-2(3H)-one, and tetrahydrofuran. Mechanistic experiments were performed to support the proposed mechanism.

Automated summary

Here we present a simple photochemical method for constructing phenanthridines with synthetically useful succinate units. The reaction proceeds under visible-light irradiation using cheap eosin Y Na as the photoredox catalyst and a diazo compound as the succinate precursor. A wide range of phenanthridines are obtained in moderate to good yields under the optimal conditions. The succinate units in the final heterocycles can be easily transformed into valuable structures such as gamma-butyrolactone, dihydrofuran-2(3H)-one, and tetrahydrofuran. Mechanistic experiments support the proposed mechanism.