Synthesis of α-(Trifluoromethyl)styrenes and 1,3-Di(trifluoromethyl)indanes via Electrophilic Activation of TMS Ethers of (Trifluoromethyl)benzyl Alcohols in Brønsted Acids

Olesya V Khoroshilova; Irina A Boyarskaya; Aleksander V Vasilyev

doi:10.1021/acs.joc.2c01961

Synthesis of α-(Trifluoromethyl)styrenes and 1,3-Di(trifluoromethyl)indanes via Electrophilic Activation of TMS Ethers of (Trifluoromethyl)benzyl Alcohols in Brønsted Acids

J Org Chem. 2022 Dec 2;87(23):15845-15862. doi: 10.1021/acs.joc.2c01961. Epub 2022 Nov 17.

Authors

Olesya V Khoroshilova¹, Irina A Boyarskaya¹, Aleksander V Vasilyev^{1

2}

Affiliations

¹ Department of Organic Chemistry, Institute of Chemistry, Saint Petersburg State University, Universitetskaya nab., 7/9, Saint Petersburg 199034, Russia.
² Department of Chemistry, Saint Petersburg State Forest Technical University, Institutsky per., 5, Saint Petersburg 194021, Russia.

PMID: 36394446
DOI: 10.1021/acs.joc.2c01961

Abstract

TMS ethers of CF₃-benzyl alcohols (and their heterocyclic analogues) undergo elimination of TMSOH molecule with the formation of α-(trifluoromethyl)styrenes in yields of up to 90% under the action of strong Brønsted acids TfOH or H₂SO₄. Under the acidic conditions upon prolongation of the reaction, the α-(trifluoromethyl)styrenes are further dimerized into cis-/trans-1,3-di(trifluoromethyl)indanes in yields of up to 100%. Plausible reaction mechanisms of these electrophilic transformations including the intermediate formation of CF₃-benzyl carbocations are discussed.