Mono- and dicyclic unsaturated triterpenoid hydrocarbons in ...

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884 R. de Mesmay et al. / Organic Geochemistry 39 (2008) 879–893 relative intensity % 100 50 0 % 100 50 0 % 100 50 0 relative intensity 43 33 71 C 28 125 85 111 H1 C 29 H2 42 44 46 48 retention time (min.) 125 141 167 236/237 211 and j are higher homologues of the C34 masokocene c (Figs. 2 and 7). The EI mass spectrum of e is consistent with a C35H60 botryococcene (M +. at m/z 480; Fig. 7A). It exhibits prominent fragments at m/z 123 and 177, suggesting the 236 294/295 294 446/447 H2 337 386 431 446 M +. -C2H5 50 100 150 200 250 300 350 400 450 m/z H3 H3 % 100 50 0 H3 H3 C 31 H4 H4 H5 H6 H6 71 85 111 43 236 141 167 197 253 322 295 349 391 435 459 474 69 83 125 139 43 167 236 306 195 277 251 335363389 429 459 125 322/323 474/475 -C2H5 (on C-21) 306/307 277 458/459 139 125 236/237 125 459 H4 236/237 H5 50 100 150 200 250 300 350 M 400 450 m/z 50 100 150 200 250 300 350 400 450 m/z +. % 100 50 -C2H5 0 M +. -C2H5 43 71 85 111 236 141 167 197 336 267295 363 419 464 488 125 125 236/237 336/337 488/489 H6 69 111 83 139 125 125 153 167 236/237 320/321 472/473 H7 153 473 50 100 150 200 250 300 350 400 450 m/z 43 50 100 150 195 236 251 200 250 M 293 473 320 363 388415 300 350 400 450 m/z +. M -C2H5 +. % 100 50 -C2H5 0 43 69 83 111 125 139 167 125 209 236 236/237 H7 -CH3 (on C-21) 292/293 277 444/445 H3 292 277 321349 379 M 445 429 +. -C2H5 50 100 150 200 250 300 350 400 450 m/z Fig. 3. (A) Total ion chromatogram of hydrogenated hydrocarbon fraction from 1856–1871 cm depth sediment interval from Lake Masoko (C xx are n-alkanes with xx carbon atoms). (B–G) EI mass spectra of botryococcanes H2-H7. presence of a trimethyl substituted cyclohexenyl ring in the left hand part of the molecule, as in c. The presence of two rings in e is supported by the mass spectra of the several diastereomers of C35 botryococcanes H5 formed 125
Table 2 1 H [400 MHz; dH (J, Hz)] and 13 C [100 MHz; d C] NMR data of C 34 masokocene c in CDCl 3 at 300 K Position 1 H(dH) 13 C(dC) HMBC (H ? C) 1, 30 0.78 (6H, s) 23.4 2, 3, 23, 24 a 2, 21 34.5 3, 20 1.41 (2H, m) 38.5 1, 2, 4, 5, 23, 31 a 4, 19 1.26-1.42 (4H, m) 28.1 6 a 5, 18 1.86 (H-5a, H-18a, m) 24.9 3, 4, 6, 24 a 1.78 (H-5b, H-18b, m) 3, 4, 6, 24 a 6, 17 138.3 7 1.90 (1H, m) 41.4 6, 8, 9, 32 8 1.12-1.23 (2H, m) 29.6 7, 9, 10 9 1.24 (2H, m) 39.0 8, 10, 11, 25, 26 10 41.8 11 5.26 (1H, d, 16.0) 135.8 9, 10, 12, 13, 25, 26 12 5.12 (1H, dd, 16.0, 7.7) 133.9 10, 11, 13, 26, 28 13 2.03 (1H, m) 37.1 11, 12, 14, 28 14 1.10-1.25 (2H, m) 35.1 12, 13, 15, 16, 28, 33 15 1.15-1.30 (2H, m) 32.7 13, 14, 16, 33 16 1.94 (1H, m) 40.9 14, 15, 17, 18, 29, 33 22, 23 0.95 (6H, s) 29.5 1, 2, 3, 24 a 24, 29 5.03 (2H, s) 132.7 1, 2, 3, 5, 7, 23 a 25 1.01 (3H, s) 23.8 9, 10, 11, 12, 26, 27 26 5.75 (1H, dd, 17.3, 10.7) 147.3 9, 10, 11, 25 27 4.90 (H-27a, dd, 17.3, 1.5) 110.9 10, 26 4.92 (H-27b, dd, 10.7, 1.5) 10, 26 28 0.94 (3H, d, 6.4) 21.2 11, 12, 13, 14, 15 31, 34 0.86 (6H, d, 6.4) 16.2 2, 3, 4 a 32 0.94 (3H, d, 6.4) 19.8 b 5, 6, 7, 8 33 0.94 (3H, d, 6.4) 19.9 b 15, 16, 17, 18 a Only correlations concerning proton on the left hand part of molecule given. b Signals interchangeable. 25 10 27 28 13 31 substructure I substructure II 2 6 24 HMBC 1 3 5 23 24 7 32 by stereochemical isomerization during hydrogenation (Fig. 3A and E). A fragment ion at m/z 458/459 (due to the loss of the ethyl at C-10) supports the presence of two rings in H5. Moreover, fragment ions at m/z 236/237 and 306/307, originating from C-10/C-11 and C-9/C-10 cleavage, respectively, indicate the presence of one ring in each side of H5. The ion at m/z 306/307 in the H5 spectrum indicates that the additional carbon is situated on the right hand side of the molecule compared to H3. The position of this additional carbon in e was deduced from its ozonolysis products. Comparison of the mass spectrum of O10 (C17H30O3) with that of O9 (C16H28O3; Fig. 6E and F) indeed indicates the presence of an ethyl in O10, (M +. - C2H5; fragment at m/z 253). McLafferty rearrangement leading to ion at m/z 86 indicates that the ethyl group is likely carried by carbon C-21. In the mass spectrum of e (Fig. 7A), the loss of an ethyl is also suggested by an ion at m/z 451. Thus, on the basis of all these mass spectral data we propose structure e for the C35 masokocene. The EI spectrum of the C 36 botryococcene j (C 36H 62,M +. at m/z 494, Fig. 7B) exhibits an intense ion at m/z 465 due to the loss of an ethyl. The hydrogenated fraction contains several C36 botryococcanes (C36H70, H7) with identical mass spectra (e.g. Fig. 3A and G). Diagnostic ions at m/z 236/237 and 125 suggest the presence of a trimethylated cyclohexyl in the left moiety of the molecule as in H3 and H5. By comparison with H5, the ion at m/z 320/321 indicates that the additional carbon is located in the right part of the molecule. An intense peak at m/z 153 (57%) is consistent with a cyclohexane ring substituted with one more carbon in H7 than in H5. The mass spectrum of j exhibits a M + -Et fragment (m/z 23 Me 1 Me Me 31 NOE Fig. 4. Selected HMBC and NOE correlations in NMR analysis of C 34 masokocene c. 26 10 11 R. de Mesmay et al. / Organic Geochemistry 39 (2008) 879–893 885 12 c 16 29 17 21 O 3 Fig. 5. Ozonolysis products of C 34 masokocene c. H O O 12 H 16 O + O H O9 17 18 24 O11 H O 21 29 26 O 2 10 24 11 6 O Me H H
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