The use of lithioethylenediamine as a dehydrogenating and isomerizing reagent has been further extended and applied to new mono-, sesqui- and diterpenes. Structures of reaction products, including the phenol (XXVII), recently obtained as a degradation product of copaene, were decided on the basis of IR, UV and NMR spectral studies. Some of the transformations carried out with the help of this reagent