rac-2,2 0 -Diamino-3,3 0 -diethoxycarbonyl-8,8 0 -diphenyl-1,1 0 -biazulene was synthesized from diethyl 2-aminoazulene-1,3-dicarboxylate and was optically resolved into two enantiomers of S-form and R-form. The enantioselective oxidative couplings with two chiral amines [(2)-sparteine and (R)-(þ)-a-methylbenzylamine] and ferric chloride catalyst, and the asymmetric couplings with two chiral oxovanadium(IV) complexes of ethyl 2-amino-4-phenylazulene-1-carboxylate, easily yielded chiral 2,2 0 -diamino-3,3 0 -diethoxycarbonyl-8,8 0 -diphenyl-1,1 0 -biazulene. Therefore, the introduction of two phenyl groups at the 8-and 8 0 -postions of each azulene ring using phenyl magnesium bromide via an addition-oxidation-decarboxylation mechanism resulted in 1,1 0 -biazulene forming a chiral C 2 axis.
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