Synthesis 2002(4): 0491-0496
DOI: 10.1055/s-2002-20963
PAPER
© Georg Thieme Verlag Stuttgart · New York

Efficient Mono- and Dilithiation of 2-Bromo-1,1-diphenylethene with n-Butyllithium/Tetramethylethylenediamine

Sergei M. Korneev*a,, Dieter E. Kaufmannb
a Institute of Chemistry, St. Petersburg State University, University Pr.2, 198504 St. Petersburg, Russia
e-Mail: sergei.korneev@gmx.de;
b Institute of Organic Chemistry, Technical University of Clausthal, Leibnizstr.6, 38678 Clausthal-Zellerfeld, Germany
Further Information

Publication History

Received 10 September 2001
Publication Date:
28 July 2004 (online)

Abstract

Lithiation of 2-bromo-1,1-diphenylethene (2) with n-butyllithium or tert-butyllithium/tetramethylethylenediamine (TMEDA) in pentane at -100 °C effects a halogen-lithium exchange to give 2-lithio-1,1-diphenylethene (3) exclusively, which reacts with electrophiles to provide 2-substituted-1,1-diphenylethenes 5-8 in high yields. Further lithiation of the monolithium derivative 3 with n-butyllithium/TMEDA results in the direct ortho-lithiation of Z-located phenyl ring to give dilithium derivative 9, which forms disubstituted ethenes 11-13 or heterocycles 15-17 on treatment with electrophiles. tert-Butyllithium/TMEDA is ineffective for the second lithiation step.

1

Current address: Institute of Organic Chemistry, Georg-August-Universität Göttingen, Tammannstr.2, 37077 Göttingen, Germany. Fax: +49(551)399475; E-mail: sergei.korneev@gmx.de.

14

One equivalent of n-BuLi is required for the metalation of 2 to 3. The second equivalent reacts with butyl bromide formed to turn the metalation equilibrium to the side of products: 2 + BuLi → 3 + BuBr, BuLi + BuBr → Bu-Bu + LiBr.

22

Acetone-d 6 was used as internal standard, δ = 2.05.