Skytanthines

When racemic mevalonic acid as the corresponding lactone and labeled at C-2 with is fed to the Chilean shmb SJ tanthus acutusM.ejen. labeled p-skytanthine [24282-31-3] (115) is obtained. Skjtanthus alkaloids are reputed to be tremorgenic (85). 

P-parinaric acid, physical properties, 5 33t P-pentenoic acid, physical properties, 5 3 It P-peroxylactones, 18 484 Beta phase titanium, 24 838 in alloys, 24 854-856 properties of, 24 840, 941 P-phellandrene, 24 493 P-picoline, 21 110 from acrolein, 1 276 uses for, 21 120 P-pinene, 3 230 24 496-497 major products from, 24 478 /-menthol from, 24 522 as natural precursor for aroma chemicals, 3 232 terpenoids from, 24 478-479 P-propiolactone, polymerization of, 14 259 P-quartz solid solution, 12 637—638 Beta ratio, in filtration, 11 329—330 Beta (P) rays, 21 285 P-scission reactions, 14 280-281 P-skytanthine, 2 101 P-spodumene solid solution, 12 638-639 P-sulfur trioxide, 23 756 P-sultones, 23 527 P-tocopherol, 25 793 P-tocotrienol, 25 793 P-vinylacrylic acid, physical properties, 5 33t... 

Terpenoid alkaloids Apocynaceae Skytanthus acutus /3-skytanthin... 

The homochiral f -branched carboxylic acids (13 or enf-13 Table 1) have been used for the synthesis of a variety of natural products21 such as California red scale pheromone,14 a-skytanthine,22 the southern com rootworm pheromone,15 and norpectinatone.16 Pure (5)-3-trichloromethylbutyric acid (a structural subunit of some sponge metabolites) was prepared via conjugate addition of ClaCMgCl to the chiral cro-tonate (16) followed by hydrolysis (Scheme S).23... 

The monoterpene alkaloids constitute a relatively small group of compounds and their occurrence has been restricted to several species of the genus Kopsia, viz., K. pauciflora, K. macrophylla and K. dasyrachis, from which several new monoterpene alkaloids related to skytanthine have been recently isolated. 

The spectral data for kinabalurine D (47) showed it to be yet another 7-hydroxy-skytanthine diastereomer but proved inadequate for definitive assignment of stereochemistry. To this end kinabalurine D was converted to the quaternary ammonium iodide salt which provided suitable crystals for X-ray analysis. Kinabalurine D differs from kinabalurines A-C in having a 4-P-methyl group and a trans ring junction in which the stereochemistry of H(5)... 

The second monoterpene alkaloid kopsone gave a molecular, ion which analysed for C11H19NO. The IR (1720 cm ) and C NMR (8 218) spectral data indicated the presence of a ketone function. Other groups indicated by the NMR spectra were two CHMe groups, an N-methyl, three methylenes (one deshielded at 8 56) and four methines (one deshielded at 8 72). These, as well as a postulated common origin of 51 and 52 from the hypothetical 9-hydroxy-skytanthine precursor 53 (Scheme 1), led to the proposed structure for kopsone. The relative stereochemistry was deduced from analysis of the H NMR spectrum. 

The leaves of K. dasyrachis gave kopsirachine (54), which is constituted from union of the flavonoid, catechine and two units of skytanthine. The gross structure was deduced from spectral and chemical evidence but the stereochemistry of the skytanthine units in 54 remains to be firmly established [57]. 

A new monoterpene alkaloid, kinabalurine G (330) has been obtained from the leaf extract of Kopsia dasyrachis in addition to 11 known alkaloids and the novel pentacyclic indole, danuphylline vide infra) [223]. Analysis of the spectral data allowed assignment of the gross structure as well as determination of the stereochemistry at the various centers. Kinabalurine G (330) is the AZ-oxide of 9-hydroxy-S-skytanthine, which is unknown, although a 9-hydroxy-skytanthine of unknown stereochemistry has been previously reported from Tecoma stans [224]. 

The Hofmann reaction of various stereoisomers of skytanthine methiodides has been studied directly in the gas chromatograph. The conformational differences are important in determining the direction and extent of / -elimination, as opposed to regeneration of the tertiary amines. A mass spectral study of one Gentiam alkaloid has been reported. ... 

The bark of Tecoma arequipensis (Bignoniaceae) yielded a major alkaloid, (-)-S-A-nor-methylskytanthine (32), [a]D -21.5°, whose structure was established through X-ray crystallographic analysis of the N-(4-bromophenylthiourea) derivative (36). Other alkaloids detected by GC-MS analysis included 5,6-dehydroskytanthine, skytanthine, actinidine, 5-hydroxy-skytanthine and tecomanine. Additional components were partially characterized (MS data only) as two hydroxytecomanines and four... 

Originally isolated as Alkaloid C by Jones and Dickinson (45), the structure was deduced to be that of a 5- or 9-hydroxy-skytanthine derivative, with the former structure preferred. To clarify this ambiguity the methiodide salt was subjected to X-ray crystallographic analysis (46,47), which showed that the isolate was 5/3-hydroxy-skytanthine (44). The same compound was also isolated from the fruits of Tecoma starts, and the proton and 13C NMR data were established (42). 

The leaves of T. starts revealed two polar skytanthine derivatives, which were partially characterized as S-skytanthine (33), 5-hydroxy-skytanthine (44) (Rf 0.14), N-nor-methylskytanthine (32), or tecostanine (45) (Rf 0.06) by TLC (89). 

The leaves of Tecoma stans (Bignoniaceae) were studied previously (1) because of their reputed antidiabetic properties, which appear to have been traced to the monoterpene alkaloid fraction. Further studies of this plant by Lins and D arc Felicio (42) have now revealed the presence of two new alkaloids, 7-hydroxy-5,6-dehydroskytanthine (58) and 4-hydroxy-tecoman-ine (59), in the fruits of T. stans. In addition, two known alkaloids, 5/3-hydroxy-skytanthine (44) and tecomanine (55) were obtained. H and 13C NMR data for these known alkaloids were reported for the first time. 

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