Mass-spectrometric distinction of linear and angular 2,2'-dimethyl-3'-oxo-dihydropyranocoumarins

Summary The mass spectra of linear and angular 2,2-dimethyl-3-oxodihydropyranocoumarins and their deuterium analogs have been studied. A basic mass-spectrometric difference between these substances has been found which consists in the greater stability of the fragment (M - CO)⁺. for the linear isomer than for the angular isomer. A hypothesis has been put forward on the most probable route for the formation of the ion (M - 2CO - H)⁺ in the mass spectra of the compounds mentioned.M. V. Lomonosov Moscow State University. Patrice Lumumba International Friendship University, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 664–668, September–October, 1977.