Mass spectrometric studies of diterpenes: VIII—Epimers

Abstract

Diterpene epimers differing with respect to orientation of a secondary hydroxyl group, ring fusion or configuration at an asymmetric centre carrying carbon-carbon linked substituents were studied, and certain stereostructural-spectral correlations were achieved for the first two groups. Each of the compounds examined was subjected to multiple scanning at both high and low electron voltage to allow computer assisted statistical calculation and comparison of intensity intervals at a predetermined confidence level for total ion currents and selected peaks.

Intramolecular hydrogen transfer in mass spectra. III. Rearrangements involving the loss of small neutral molecules

“…In two of these studies various epimeric diterpene alcohols were utilized as substrates, and it was concluded that both cis 1,3-and cis 1,4-eliminations occurred stereospecifically provided that the hydrogen abstracted was tertiary. 1233 in the other study, water elimination from some adamantane derivatives was investigated.1234 Water loss has also been noted from various other molecular structures, including acetylated 2,2'-diaminodiphenylmethanes,1235 phthalazinone derivatives,1236 the m/e 99 fragment ion of dialkyl phosphates,1237 a fragment ion from certain 4,6-diaikyl-1,3dioxanes,1238 and the (M -CH3)+ fragment ion of ethyl 2ethoxybenzoate.1239 In addition, the unusual loss of HO• from various bipiperidyl alkaloids containing an amide function has been studed in detail. 1240 The loss of methanol from 4-fezt-butylcyclohexyl methyl ether under photoionization conditions occurs more readily from the trans isomer which also has the more abundant molecular ion; a 1,4-mechanism is proposed for this elimination.…”