The first synthesis of optically pure (+)- and (−)-isokotanin A and the assignment of their absolute configuration
作者:Guo-Qiang Lin、Min Zhong
DOI:10.1016/0040-4039(96)00457-1
日期:1996.4
The first asymmetric synthesis of optically pure (+) and (−)-Isokotanin A is described. The key steps involve the asymmetric Ullmann coupling and selective demethylation. The absoluteconfiguration of the naturally occuring (+)-Isokotanin A is assigned as aR.
In this report a new atroposelective total synthesis of (+)-isokotanin A is described. The combination of metal- and enzyme catalysis facilitates a scalable route towards the key axially chiral 2,2′-biphenol building block. We established a one-pot Miyaura-Suzuki homocoupling towards the tetra-ortho-substituted biphenol on a decagram scale, applying Buchwald's precatalyst PdG4SPhos and SPhos in low
The atropo-enantioselective total synthesis of the axially chiral bicoumarin (+)-isokotanin A (1) is described. Key steps were the formation of a configurationally stable seven-membered biaryl lactone and its kinetic resolution by atroposelective ring cleavage, The previous assignment of the absolute configuration of (+)-isokotanin A (1) (and its synthetic precursors) was confirmed by quantum chemical CD calculations. (C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.