Desymmetrization of Symmetrical Triarylcarbinols: Synthesis of 7-Arylfluorenes and a C-2-Symmetric Chiral BIFOL Phosphoric Acid

作者：Someshwar Nagamalla; Karthick Muthupandi; Ramanathan Chinnasamy Ramaraj^*

来源：Synlett, 2017, 28(17): 2253-2261.

DOI：10.1055/s-0036-1589074

• benzofluorenes
• ligands
• asymmetric synthesis
• triarylcarbinols
• cyclization
• transfer hydrogenation

A simple and an efficient method for the synthesis of 7-arylfluorenes by intramolecular cyclization of the corresponding triarylcarbinols in the presence of the solid-acid catalyst NaHSO4/SiO2 has been developed. By using this method, a new chiral diol with a C2-symmetric bisfluorenyl unit, 7,7'-diphenyl-7H, 7' H-5,5'-bibenzo[c] fluorene-6,6'diol (BIFOL), having central chirality was synthesized in an optically active form from (S)-(-)-BINOL-3,3'-dicarboxylic acid. The absolute configuration of the chiral bisfluorene derivative BIFOL was ascertained by single-crystal X-ray analysis. Furthermore, a new chiral phosphoric acid was synthesized from BIFOL and evaluated for enantioselective transfer hydrogenation.

• 出版日期2017-10