Stereochemistry of the Bucherer–Bergs and Strecker reactions of tropinone, cis-bicyclo[3.3.0]octan-3-one and cis-3,4-dimethylcyclopentanone
1979 ◽
Vol 57
(12)
◽
pp. 1456-1461
◽
The tropane-3-spiro-5′-hydantoin (α isomer) obtained from tropinone by the Bucherer–Bergs reaction has been shown by 13C nmr and X-ray diffraction studies to have the 4′-carbonyl group in the equatorial position; the β isomer, obtained via the Strecker reaction, has this group axial. The results of these two reactions on cis-bicyclo[3.3.0]octan-3-one and on cis-3,4-dimethylcyclopentanone show, on the basis of the 1H nmr, 13C nmr, and X-ray diffraction studies of the products, a stereochemical course related to the preferred conformation of the cyclopentane rings.