Mass Spectral Study of Ring E of Taraxasterol and Compounds with Similar Ring Substitution
Mass Spectral Study of Ring E of Taraxasterol and Compounds with Similar Ring Substitution
- Organic Mass Spectrometry, 20(3), p.247-252, 1984 .
The origin of the [M-69]+ and [M- 111]+ signals in the mass spectrum of taraxasterol was studied through the use of C(18), (19), (21), (22)and/or (30)deuteriated derivatives. The generality of these signals for ring systems with an exocyflic methylene group and a methyl moiety on an adjacent carbon was verified with 2-methylmethylenecydohexane, l-methyl-2-methylene-trans-decalin, l,lO-dimethyl-2-methylene-transdecalin and some of their deuteriated derivatives. The most plausible mechanism for the formation of the [M-69]+ ion appears to involve cleavage of both bonds allylic to the exocyclic methylene group with a 1,3-hydrogen transfer from the adjacent ring. Genesis of the [M-111]+ ion is more complicated but B five-membered allylic ion generated from ring D is proposed.
The origin of the [M-69]+ and [M- 111]+ signals in the mass spectrum of taraxasterol was studied through the use of C(18), (19), (21), (22)and/or (30)deuteriated derivatives. The generality of these signals for ring systems with an exocyflic methylene group and a methyl moiety on an adjacent carbon was verified with 2-methylmethylenecydohexane, l-methyl-2-methylene-trans-decalin, l,lO-dimethyl-2-methylene-transdecalin and some of their deuteriated derivatives. The most plausible mechanism for the formation of the [M-69]+ ion appears to involve cleavage of both bonds allylic to the exocyclic methylene group with a 1,3-hydrogen transfer from the adjacent ring. Genesis of the [M-111]+ ion is more complicated but B five-membered allylic ion generated from ring D is proposed.