Divergent Total Syntheses of C3 a−C7′ Linked Diketopiperazine Alkaloids (+)‐Asperazine and (+)‐Pestalazine A Enabled by a Ni‐Catalyzed Reductive Coupling of Tertiary Alkyl Chloride

Short gram-scale asymmetric syntheses of asperazine, pestalazine A, and their unnatural congeners thereof, have been achieved in approximate to 10 steps by using readily accessible starting materials. The nickel-catalyzed reductive coupling protocol was utilized as a key step for the direct construction of C3a(sp3)-C7 '(sp2) bond furnishing the diaryl-substituted quaternary carbon centers with remarkable steric hindrance. The streamlined access to this core structure of heterodimeric tryptophans under the mild reaction conditions, makes this strategy hold a great promise in the concise synthesis of other relevant oligomeric pyrroloindoline alkaloids with unique C3a-C7 ' linkages.