3,7,9-Triheterabicyclodecan-10-ones: An Unusual Family of Heterocycles Obtained from 3,7-Diheterabicyclononan-9-ones

Article abstract of DOI:10.1021/jo00079a009

A series of new 3,7,9-triheterabicyclo<3.3.2>decan-10-ones is reported for the first time.Members of the family of 3,7-diheterabicyclo<3.3.1>nonan-9-ones served as precursors of the title compounds.Spectral evidence suggests the 3,7,9-triheterabicyclo<3.3.2>decan-10-ones exist in a chair-boat (CB) ->/<- boat-chair (BC) equilibrium in solution.It is speculated that steric hindrance around the carbonyl group and possibly the variance in conformation BC versus CC of the individual 3,7-diheterabicyclo<3.3.1>nonan-9-one precursors in solution may influence the ease of oxygen and nitrogen insertion in the ring enlargement to give the title molecules.Confirmation that three members of the bicyclo<3.3.2>decan-10-ones exist in BC forms in the solid state was achieved via single crystal X-ray diffraction analysis for 7-benzyl-3-thia-7,9-diazabicyclo<3.3.2>decan-10-one (4a), 3,7-dibenzyl-3,7,9-triazabicyclo<3.3.2>decan-10-one (4c), and 3,7-dibenzyl-9-oxa-3,7-diazabicyclo<3.3.2>decan-10-one (4d).