Dehydrogenation studies in the field of indole alkaloids

Two methods of dehydrogenation have been used for the oxidation of variously ring E-substituted yohimbine- and ajmalicine-type indole alkaloids;The first method, palladium-maleic acid dehydrogenation, produces ring C tetradehydro compounds and can be used for differentiating pseudo compounds from epiallo compounds. The second method, mercuric acetate oxidation, produces 3-dehydro compounds;By the use of the first method the stereochemistry of several indole alkaloids was elucidated;Infrared spectra in the C-H stretching region (3.4--3.7mu) have been used for differentiating between C3 epimers of indole alkaloids;Structures were proposed for several new compounds derived by oxidation or reduction of indole alkaloids or their derivatives;The stereochemistry of various reduction methods was discussed