Theoretical Investigation on Intramolecular Friedel-Crafts Alkylation Of 2,2′-Disubstituted 1,3-Indandione Delivering Axially Chiral Biaryls Catalyzed by Chiral Phosphoric Acid

Abstract

Our Density Functional Theory (DFT) calculations provide the first theoretical investigation on CPA-catalyzed intramolecular Friedel-Crafts alkylation of 1,3-indandione. The reaction is initiated by bis-coordination of CPA with carbonyl and phenol of indandione. The promotion of CPA lies in H-bridge and steric effect from big silyl substituents confirming less-hindered Re-face more favorable than more-shielded Si-face within central chiral alcohol. Next AlCl3-promoted process contains four steps. The dehydration gives positive carbocation, the rearrangement of which activates another carbonyl. The water reversely splits into hydrogen and hydroxyl to recover phenol. The naphthol is obtained from opening of five-membered ring. The central-to-axial chirality conversion is secured between methyl/phenol substituents and carboxylic moiety of axially chiral biaryls. The positive solvation effect is suggested by decreased absolute and activation energies in solution compared with in gas. These results are supported by Multiwfn analysis on FMO composition of specific TSs, and MBO value of vital bonding, breaking.