- Total syntheses of tacamide-type indole alkaloids of Tabernaemontana eglandulosa
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Total syntheses are described for seven tacamine-type indole alkaloids (1-7) found in Tabernaemontana eglandulosa. (±)-Tacamine (1), (±)-16-epitacamine (2), and (±)-apotacamine (3) were prepared from pentacyclic intermediates 18. Apotacamine (3) was also obtained from aldehyde 12 via epimerization of 20-epiapotacamine (19) by the Polonovski-Potier reaction. Homologation of ester 13 led to 20-epitacamonine (23), which was similarly converted to (±)-tacamonine (4). Reduction of 4 gave (±)-descarbomethoxytacamines 5 and 6. Aldehyde 11 was reacted with trimethylsilyl cyanide (TMSCN) to yield the two (±)-17-hydroxytacamonines (7), of which the isomer with an axial hydroxy group (17β-OH) was found to be identical with the natural compound. Finally, an attempt to prepare (±)-19S-hydroxytacamine (8) is described. As an intermediate for this, a new synthesis of the pyridine alkaloid methyl 5-(1'-hydroxyethyl)nicotinate (34) was achieved.
- Din Belle, David,Tolvanen, Arto,Lounasmaa, Mauri
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- Synthesis and promotion of the osteoblast proliferation effect of morroniside derivatives
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Sambucus williamsii Hance has been used in fractures for thousands of years, but research on its active components, such as morroniside, until now had not been carried out. In this study, morroniside was taken as the leading compound, and fourteen derivatives were synthesized. The promotion of osteoblast proliferation effect of the derivatives was evaluated on MC3T3-E1 cells. Five derivatives (2, 3, 4, 5, and 14) showed a good proliferation effect on MC3T3-E1 cells, and their promoted expression effects on OC (Osteocalcin) and ALP (Alkaline phosphatase) in MC3T3-E1 cells were measured. Compound 3 was shown to have the strongest proliferation effect (EC50 = 14.78 ± 1.17 μg/mL) and to significantly promote the expression of OC and ALP.
- Han, Hua,Li, ZhengQing,Qu, Na,Chen, Si,Dong, PeiLiang
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- Total Synthesis of the Proposed Structures of Indole Alkaloids Lyaline and Lyadine
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The harman-1,4-dihydropyridines 1 and 2, which constitute the originally proposed structures for the indole alkaloids lyaline and lyadine, have been synthesized, and their NMR data have been compared with those available for the natural products. Due to the discrepancies in the spectral data, the structures of lyadine and lyaline should be revised.
- Bennasar, M.-Lluisa,Roca, Tomas,Monerris, Manuel
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p. 752 - 756
(2007/10/03)
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