Acid-Catalyzed Versus Thermally Induced C1-C1' Bond Cleavage in 1,1'-Bi-2-naphthol: An Experimental and Theoretical Study

Alexander M Genaev; Lyudmila N Shchegoleva; George E Salnikov; Andrey V Shernyukov; Leonid A Shundrin; Inna K Shundrina; Zhongwei Zhu; Konstantin Yu Koltunov

doi:10.1021/acs.joc.9b00915

Acid-Catalyzed Versus Thermally Induced C1-C1' Bond Cleavage in 1,1'-Bi-2-naphthol: An Experimental and Theoretical Study

J Org Chem. 2019 Jun 7;84(11):7238-7243. doi: 10.1021/acs.joc.9b00915. Epub 2019 May 22.

Authors

Alexander M Genaev¹, Lyudmila N Shchegoleva¹, George E Salnikov^{1

2

3}, Andrey V Shernyukov^{1

2}, Leonid A Shundrin^{1

2}, Inna K Shundrina^{1

2}, Zhongwei Zhu², Konstantin Yu Koltunov^{2

4}

Affiliations

¹ N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry , Pr. Akademika Lavrentieva 9 , Novosibirsk 630090 , Russia.
² Novosibirsk State University , Pirogova 2 , Novosibirsk 630090 , Russia.
³ International Tomography Center , Institutskaya 3a , Novosibirsk 630090 , Russia.
⁴ Boreskov Institute of Catalysis , Pr. Akademika Lavrentieva 5 , Novosibirsk 630090 , Russia.

PMID: 31083942
DOI: 10.1021/acs.joc.9b00915

Abstract

Experiments show that 1,1'-bi-2-naphthol (BINOL) undergoes facile C1-C1' bond cleavage under action of triflic acid at temperatures above 0 °C to give mainly 2-naphthol along with oligomeric material. CASSCF and MRMP//CASSCF computations have demonstrated unambiguously that this unusual mode of scission of the biaryl bond can occur in the C1,C1'-diprotonated form of BINOL via a mechanism involving homolytic cleavage prompted by the intramolecular electrostatic repulsion. These findings also provide insights into the mechanism of a comparatively easy thermal cleavage of BINOL, implying the intermediacy of its neutral diketo form.