CONFORMATIONAL STUDY OF CINCHONA ALKALOIDS - A COMBINED NMR AND MOLECULAR-ORBITAL APPROACH

1D and 2D NMR techniques have been used to elucidate the conformational behavior of cinchona alkaloids in solution. Deoxy, chloro, methoxy, and benzoyl derivatives have been studied together with the unsubstituted alkaloids. Semiempirical molecular orbital calculations (AM1) on segments as well as on the complete structures of cinchona alkaloids have given complementary quantitative information. These calculational results have been used to rationalize the experimentally obtained conformational data and to shed light on the subtilities involved that determine the conformation of cinchona alkaloids. © 1990, American Chemical Society. All rights reserved.