Mass spectrometry of bisquinolizidine alkaloids: 2- and 15-substituted derivatives of sparteine and 2- (or 14)-dehydrosparteine

Mass spectrometry of bis-quinolizidine alkaloids: 2- and 17-alkyl-substituted derivatives of sparteine and lupanine

“…On the basis of the low‐resolution EI mass spectra, exact mass determinations (Tables 1 and 2) and CAD B / E as well as B 2 / E linked scan spectra (Figs 2 and 3), the principal mass spectral fragmentation routes of compounds 1–3 are interpreted as shown in Scheme , and those of 4 and of 5 and 6 as in Schemes and 3 respectively. It should be pointed out that only the fragmentation pathways have been confirmed by B / E and B 2 / E linked scan spectra and that many of the cyclic ion structures shown in Schemes are conjectural, similarly to those discussed previously in the literature 1–10. The common feature of the mass spectral fragmentation of molecular ions of 1–6 is the cleavage of N1–C10, C6–C7, C9–C10 (ring B), C9–C11, C7–C17 (ring C) as well as C17–R (RCH 3 , i ‐C 3 H 7 ) (ring C) and C2–CH 3 (ring A) bonds of the skeleton of sparteine.…”

“…The main characteristic of the mass fragmentation of the molecular ions of these compounds is the dependence of the mass decomposition of the bis‐quinolizidine skeleton on the stereochemistry of the A/B and C/D ring junctions 5. As a continuation of our study of the mass fragmentation of lactams of sparteine and α‐isosparteine,6, 7 multiflorine and its derivatives,8 13‐keto‐ and hydroxy‐substituted derivatives of sparteine and lupanine9 and 2‐ and 15‐substituted derivatives of sparteine and 2‐ (or 14‐) dehydrosparteine,10 it seemed reasonable to extend our investigation to 2‐ and 17‐alkyl‐substituted derivatives of sparteine and lupanine. The purpose of this study was to explain the mass fragmentation of 2‐methylsparteine (1), 2,17‐dimethylsparteine (2), 2‐methyl‐17‐isopropylsparteine (3), 2‐methyl‐17‐oxosparteine (4), 2‐oxo‐17‐methylsparteine (17‐methyllupanine) (5) and 2‐oxo‐17‐isopropylsparteine (17‐isopropyllupanine) (6).…”

Indolizidine and quinolizidine alkaloids

“…94 The mass spectrometric fragmentation patterns of 2-and 17-alkyl derivatives of sparteine and lupanine have been reported. 95 …”

Mass Spectrometry of Bis-quinolizidine Alkaloids: Differentiation of Stereoisomers and Metamers Using ESI and FAB Mass Spectrometry

“…[1][2][3][4][5][6] The stereochemical effects that are encountered with dissociations of stereoisomers incorporating saturated heterocyclic rings are due to the spatial relationship of chemical bonds to be broken or formed. The basic bis-quinolizidine system sparteine consists of four rings, two of which (A=B) form a double-chair system of trans-quinolizidine that is relatively resistant (for thermodynamic reasons) to conformational-configurational changes.…”

“…15-Phenyl-14,15-didehydrosparteine (2) has C=D cis-fused rings with double-chair conformations. In contrast, 17-cyano-(or 17-methyl) lupanines (4,5) have A=B trans-fused rings with sofa=chair conformations and C=D trans-fused rings with boat=chair conformations. 2-Methyl-17-oxosparteine (7) has A=B trans-fused rings with double-chair conformations and C=D trans-fused rings with sofa=chair conformations.…”