ChemInform Abstract: Effect of a Trifluoromethyl Group on Molecular Structure: Competitive Mono- and Dilithiation of 1-[(Trifluoromethyl)phenyl]pyrroles.

✍ Scribed by Ferenc Faigl; Katalin Fogassy; Erzsebet Szucs; Krisztina Kovacs; Gyoergy M. Keseru; Veronika Harmat; Zsolt Bocskei; Laszlo Toke

• Publisher: John Wiley and Sons
• Year: 2010
• Weight: 36 KB
• Volume: 30
• Category: Article
• ISSN: 0931-7597
• DOI: 10.1002/chin.199940104

✦ Synopsis

Effect of a Trifluoromethyl Group on Molecular Structure: Competitive Mono-and Dilithiation of 1-[(Trifluoromethyl)phenyl]pyrroles.

-Lithiation and subsequent carboxylation of trifluoromethyl-substituted Nphenylpyrroles (I) and (VI) affords, depending on the reaction conditions used, selectively the mono-or dicarboxylated products in moderate to good yields. In contrast, for the o-trifluoromethyl analogue (X) no such chemoselectivity is achieved. Semiempirical calculations and X-ray structure elucidation are used to confirm the observed regioselectivity of lithiations. A strong effect of the o-CF 3 group on geometry and aromaticity of compound (X) is observed which is proposed to induce the low chemoselectivity. -(FAIGL, FERENC;