A novel compound from the electrosynthesis of bioactive (+)-10β, 14-dihydroxy-allo-aromadendrane

The electrochemical oxidation of (+)-10β, 14-dihydroxy-allo-aromadendrane (1) on glassy carbon electrodes was studied for the first time in acetonitrile by cyclic voltammetry and controlled potential electrolysis. Parameters involving data from cyclic voltammetry and controlled potential electrolysis, such as Ip versus c°, Ipν−1/2 versus ν, Ep versus −log(RTc°/Fν) and log I versus t, have shown behaviour that can be correlated to the electrochemical charge transfer competing with a zero-electron route catalysed by electrogenerated acid (EG-acid). The spectroscopy data of one isolated oxidation product show a resultant chemical coupled structure that can be justified by the formation of EG-acid from electrooxidation of 1 in order to promote the catalytic dehydration of 1 leading to the aldehyde and subsequent acetalysation to produce the novel fused spiro compound 2 (1aR,4S,4aS,7R,7aS,7bS-[decahydro-1,1,7-trimethyl-1H-cycloprop[e]azulen-4-yl]-3′-[spiro[1aR,4S,4aS,7R,7aS,7bS-[decahydro-1,1,7-trimethyl-1H-cycloprop[e]azulene-4,1′-[1,3]dioxolane]]]). The structure of 2 was elucidated by FTIR, HRMS and 1D- and 2D-NMR methods. The stereochemistry was disclosed through nuclear Overhauser enhancement spectroscopy (NOESY) experiments.