Collect. Czech. Chem. Commun.
2003, 68, 1020-1038
https://doi.org/10.1135/cccc20031020
Axially Chiral 3,3'-Bi(1-benzothiophene)-2,2'-dicarboxylic Acid and Its Derivatives
Marie Mézlováa, Hana Petříčkováb, Petr Maloňc, Václav Kozmíka and Jiří Svobodaa,*
a Department of Organic Chemistry, Institute of Chemical Technology, Prague, Technická 5, CZ-166 28 Prague 6, Czech Republic
b Department of Solid State Chemistry, Institute of Chemical Technology, Prague, Technická 5, CZ-166 28 Prague 6, Czech Republic
c Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, CZ-160 10 Prague 6, Czech Republic
Abstract
Ullmann dimerization of substituted methyl 3-X-1-benzothiophene-2-carboxylates 1-7 (X = Cl, Br) gave rise to the corresponding dimeric 3,3'-bi(1-benzothiophene) esters 8-13. Resolution of the title acid 20 by fractional crystallization of its mono- and bisquininium salt afforded pure (R)- and (S)-enantiomers, the optical purity and absolute configuration of which was confirmed by CD spectrometry and by X-ray crystallography. Ullmann dimerization of chiral oxazolines 23 and 24 derived from 2 proceeded without any diastereodifferentiation. Reduction of (R)- and (S)-20 afforded the corresponding (R)- and (S)-diols 29, which served as chiral ligands in a model enantioselective reduction of acetophenone. (R)- and (S)-1-phenylethan-1-ol were formed in 28 and 29% e.e., respectively.
Keywords: Ullmann reaction; Homocouplings; Benzothiophenes; Bi(1-benzothiophene); Resolution; Stereoselective reduction; Biaryls; Axial chirality; CD spectroscopy.
References: 49 live references.
