Practical enantioselective synthesis of axially chiral biaryl diphosphonates and dicarboxylates by cationic rhodium(I)/Segphos-catalyzed double [2 + 2 + 2] cycloaddition.
A cationic rhodium(I)/Segphos complex catalyzes a [2 + 2 + 2] cycloaddition of internal 1,6-diynes with a phosphonate- or ester-substituted 1,3-butadiyne leading to C(2)-symmetric axially chiral biaryl diphosphonates or dicarboxylates, respectively, in high yields with outstanding ee's. The use of a phosphonate- or ester-substituted 1,3-butadiyne as a cycloaddition partner and Segphos as a ligand is crucial for the success of this transformation.
Nishida
Goushi
G
Department of Applied Chemistry, Graduate School of Engineering, and Instrumentation Analysis Center, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan.
Ogaki
Shuichiro
S
Yusa
Yukinori
Y
Yokozawa
Tohru
T
Noguchi
Keiichi
K
Tanaka
Ken
K