Acid-Promoted Reaction of Trifluoromethylated Allyl Alcohols with Arenes. Stereoselective Synthesis of CF3-Alkenes and CF3-Indanes.
Reaction of 4-aryl-1,1,1-trifluorobut-3-en-2-ols [CF3-allyl alcohols, ArCH═CHCH(OH)CF3] with arenes under activation with anhydrous FeCl3 or FSO3H was studied. We found that the transformation led to trifluoromethylated alkenes [Ar(Ar')CHCH═CHCF3] or 1-trifluoromethylated indanes (CF3-indanes). The formation of these two types of reaction products strongly depends on the nucleophilicity of the starting arene and the electrophilicity of cationic intermediates generated from CF3-allyl alcohols under reaction conditions. Benzene, anisole, veratrole, and ortho-xylene lead exclusively to CF3-alkenes with an E-configuration. More π-donating polymethylated arenes (pseudocumene, mesitylene) afford only CF3-indanes with a predominantly cis-orientation of substituents at positions 1 and 3 of the indane ring. Meta- and para-xylenes show an intermediate behavior; they may form both CF3-alkenes and/or CF3-indanes. The mechanisms of the investigated transformations are discussed.
Department of Organic Chemistry, Institute of Chemistry, Saint Petersburg State University , Universitetskaya nab., 7/9, Saint Petersburg, 199034, Russia.
Anna N
AN
Kazakova
Department of Organic Chemistry, Institute of Chemistry, Saint Petersburg State University , Universitetskaya nab., 7/9, Saint Petersburg, 199034, Russia.
Roman O
RO
Iakovenko
Department of Organic Chemistry, Institute of Chemistry, Saint Petersburg State University , Universitetskaya nab., 7/9, Saint Petersburg, 199034, Russia.
Irina A
IA
Boyarskaya
Department of Chemistry, Lomonosov Moscow State University , Vorobievy Gory, 1, Moscow, 119899, Russia.
Valentine G
VG
Nenajdenko
Department of Organic Chemistry, Institute of Chemistry, Saint Petersburg State University , Universitetskaya nab., 7/9, Saint Petersburg, 199034, Russia.|Department of Chemistry, Saint Petersburg State Forest Technical University , Institutsky per., 5, Saint Petersburg, 194021, Russia.
Aleksander V
AV
Vasilyev