The pyrroloindoline alkaloids attract wide interest from the fields of chemistry, biosynthesis, and biology. From a structural perspective, they can be divided into several classes that vary in the substituent on C3a of the pyrroloindoline core, including heteroatoms, arenes, aliphatic groups, and another pyrroloindoline motif. Accordingly, a series of strategies have been developed for the synthesis of the above pyrroloindoline classes. Notably, a structurally complex aliphatic side chain linked to the C3a position is rather rare. The drimentine alkaloids (1–4, Scheme 1), which exhibit anticancer, antibacterial, antifungal, and anthelmintic properties, possess the latter substitution mode. A stereocontrolled method to form the C10b–C12 bond of the drimentine scaffold is highly desired for the synthesis of these compounds. Indotertine A (5, Scheme 1) with an unprecedented, but biosynthetically relevant, skeleton was recently discovered. The biosynthetic relationship between 3 and 5 is postulated in Scheme 1. Acidic activation of the germinal diamine moiety of 3 may generate an iminium species 6, which could undergo an iminium–olefin cyclization followed by a proton elimination of the cationic intermediate 7. Herein, we report the first total synthesis of drimentines A, G, and F (1–3), exploiting a photocatalyzed radical conjugate addition to address the problem of the C10b–C12 bond formation; a synthesis of indotertine A (5), guided by the above biosynthetic hypothesis, is also described. We first undertook a retrosynthetic analysis of drimentine G (Scheme 2). Disassembly of the diketopiperazine motif at the amide bonds followed by cleavage of the exocyclic C=C bond simplifies this molecule to core structure 8. Disconnection of the C10b–C12 bond leads to a pair of precursors (9 and 10) for an intermolecular radical conjugate addition. The former is readily available from bis(Boc-l-tryptophan) methyl ester (Boc= tert-butoxycarbonyl), whereas the latter could be derived from commercially available (+)-sclareolide (11). Scheme 1. Representative drimentine alkaloids and the postulated biosynthetic relationship between drimentine F and indotertine A.