Bicyclo[3.3.1]nonanes as Synthetic Intermediates. XV. : Ring Enlargement of Bicyclo[3.3.1]nonane-2, 6-dione and Bicyclo[3.3.1]nonan-2-one; Revision of the Literature

Abstract

The diazomethane-conducted ring expansion of bicyclo[3.3.1]nonane-2, 6-dione (1) was re-examined, and the main product, identified previously as 9-hydroxytricyclo[4.4.0.0^{2, 9}]decan-5-one (2), was shown to be 7-hydroxyisotwistan-2-one (6). The ring expansion of bicyclo[3.3.1]nonan-2-one (4) was also re-examined and the ratio of the resulting homologous ketones 10 and 11 was revised to ca. 5 : 1.