Aromatische Spirane, 17. Mitt.: Darstellung von anellierten und substituierten 2,2′-Spirobiindan-1-onen und 4,5′-disubstituierten 2,2′-Spirobiindanen

Summary

The spiroketones9, 16, and28 were prepared by cyclisation of the carboxylic acids7c, 13b, and25c and their acid chlorides, resp. (7d, 13c, and25d) with polyphosphoric acid (PPA) or SnCl₄. The precursors of the latter compounds were synthesized by alkylation of the appropriate β-ketoester1 or2 with the “benzylchlorides”3 or4 with NaH inDMF. Subsequent hydrogenation with Pd/C led to the desired alkylated indane-esters. The chiral compounds11, 17, and31 were obtained by Friedel-Crafts acetylation. The chiral disubstituted 2,2′-Spirobiindanes22 and36 were prepared from the ketones20 and32/33 by catalytic reduction followed by Friedel-Crafts acetylation.