Photoredox radical benzylation process

A method for preparing a compound of formula (I):

• wherein:
• R1, R2, R3, and R4 are independently from each other selected from the group consisting of:
• H,
• halogen,
• OH,
• (C1-C6)alkyl,
• —O(P═O)OAlk2, Alk being a (C1-C6)alkyl group,
• halo(C1-C6)alkyl,
• halo(C1-C6)alkoxy, and
• (C1-C6)alkoxy,
• R5 is selected from the group consisting of:
• (C1-C6)alkyl,
• OH,
• halogen,
• (C6-C10)aryl,
• (C6-C10)aryloxy,
• (C6-C10)aryl(C1-C6)alkyl, and
• —O—C(═O)—(C1-C6)alkyl,
• R6 is a group of formula —CH═CH2 or a group having the below formula (II):
• wherein:
• n is 0 or an integer varying from 1 to 5;
• and
• R, identical or different, is selected from the group consisting of:
• halo(C1-C6)alkyl,
• (C1-C6)alkyl,
• CN,
• NO2,
• halogen,
• —C(═O)—(C1-C6)alkyl,
• halo(C1-C6)alkoxy,
• (C1-C6)alkoxy,
• or two adjacent R groups may form together with the carbon atoms carrying them a (C6-C10)aryl group or a heterocycloalkyl group;
• said method comprising a step of reacting a compound of formula (III):
• wherein R1, R2, R3, R4, and R5 being as defined above in formula (I);
• with a compound having the following formula (IV):
• X—CH2—R6 (IV);
• wherein R6 being as defined above in formula (I), and
• X being a halogen atom;
• said reacting step being carried out under light irradiation in the presence of an iron catalyst, a heteroatomic base, and a HAT agent.