Synthesis 2008(8): 1241-1248  
DOI: 10.1055/s-2008-1042943
PAPER
© Georg Thieme Verlag Stuttgart · New York

DTBB-Catalysed Lithiation of Acenaphthylene and Reaction with Carbonyl Compounds

Victor J. Lillo, Cecilia Gómez*, Miguel Yus*
Departamento de Química Orgánica, Facultad de Ciencias and Instituto de Síntesis Orgánica (ISO), Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain
Fax: +34(965)903549; e-Mail: cgomez@ua.es; e-Mail: yus@ua.es;
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Publikationsverlauf

Received 27 December 2007
Publikationsdatum:
18. März 2008 (online)

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Abstract

The reaction of acenaphthylene with an excess of lithium powder and a catalytic amount of DTBB (7.5 mol%) in tetrahydrofuran at -70 °C followed by treatment with a carbonyl compound [Me2CO, Et2CO, i-Pr2CO, (c-C3H5)2CO, cyclopentanone, cyclohexanone, 2-adamantanone, Ph2CO, t-BuCHO] leads, after hydrolysis with water, to an easily chromatographically separable mixture of two products resulting from disubstitution at the 1,2-positions and monosubstitution at the 1-position, respectively. The reaction is regio- and stereoselective, so in the case of the disubstituted compounds only the trans-diastereomers are obtained.

12

The lithiation of acenaphthylene in tetrahydrofuran, with or without liquid ammonia, followed by trapping of the anionic intermediates with an alkyl halide leads mainly to substitu-tion at position 1 or 5, respectively (see reference 7h).

14

In reference 10b, the lithiation of acenaphthene (4) with an excess of n-butyllithium, followed by treatment with benzophenone, gave 32% of a diol resulting from 1,5-disubstitution. The physical and spectroscopic data of this diol coincide with those of our compound 6h in which the electrophilic fragments occupy the 1,2-positions.

18

As this compound was isolated in a very low yield, and the isolated product was ca. 70% pure (by GLC), the 1H and 13C NMR assignments were difficult to undertake.