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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
Author(s) -
Luo Long,
Zhai XiaoYong,
Wang YaWen,
Peng Yu,
Gong Hegui
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201805682
Subject(s) - steric effects , chemistry , alkyl , catalysis , combinatorial chemistry , total synthesis , quaternary carbon , stereochemistry , coupling reaction , chloride , enantioselective synthesis , indole test , organic chemistry
Short gram‐scale asymmetric syntheses of asperazine, pestalazine A, and their unnatural congeners thereof, have been achieved in ≈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.