Chemical examination of the alkaloids of Garrya ovata var. lindheimeri Torr. has led to the isolation and characterization of two new C20-diterpenoid alkaloids, ovatine (1) and lindheimerine (2), as well as two known alkaloids, garryfoline (3) and cuauchichicine (4). 13C NMR spectral analysis of ovatine and garryfoline reveals that each alkaloid exists as a mixture of C(20) epimers in solution. The structure of lindheimerine was confirmed by synthesis from ovatine or garryfoline via an internal Hofmann degradation. Ovatine was also prepared from lindheimerine by treatment with ethylene oxide in acetic acid. Several derivatives of ovatine and garryfoline were prepared for their 13C NMR spectral analysis. The earlier assignments of stereochemistry of the C(16) methyl group and the oxazolidine ring at C(20) in cuauchichicine have been revised by 13C NMR spectral analysis and subsequently confirmed by X-ray crystallography; cuauchichicine is the first “normal-type”, oxazolidine-ringcontaining, C20-diterpenoid alkaloid which does not exist as a pair of epimers at C(20) in solution as well as in the solid state. Certain of the previously published conclusions drawn from the correlation of cuauchichicine with (-)-”β”-dihydrokaurene are in error because of an unanticipated epimerization of the C(16) methyl group during Wolff-Kishner reduction of the intermediate ketone 23. On the basis of the revised structure of cuauchichicine, several structures assigned to derivatives of cuauchichicine have been revised. © 1981, American Chemical Society. All rights reserved.