✍ Scribed by Tóth, Gábor ;Janke, Frank ;Lévai, Albert
No coin nor oath required. For personal study only.
7.11~ dibrtimidcs 7-12 haw bccn synthesized by addition of bromint to exocyclic ell-unsaturated ketones 1-6. The rclative configurations and the swcocliemistry of the products have been dctermined by N M K methods. Bromination ol3-hcnzylideneflilwnonc (3) and its thio analogue 5 proved to be highly stereose-
Recently we investigated the synthesis of fused heterocycles by the reactions of exocyclic a$-unsaturated ketones. We obtained pyrazoline~'-~), benzothiazepines ' I, and benzodiazepines 'I. It is well-known that among the related unsaturated ketones, e.g. chalcones, the dibromides are advantageous intermediates for the preparation of various nitrogen-containing heterocycles6-'). In case of exocyclic a$-unsaturated ketones, however, only few examples are known concerning the utilization of their dibromides for such purposes'). Our aim was, therefore, the synthesis and stereochemical studies of dibromides suitable for the synthesis of fused heterocycles.
The numbering of the hydrogen and carbon atoms applied in Scheme 1 and Tables is not in accordance with IUPAC nomenclature. This modification, however, facilitates the comparison of the spectroscopically analogous atoms in compounds 7 -12.
Sgnthese und Stereochemie der Dibrnmide von ewcycliwheti or,bungesiittigtm Kctoncn
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