Sesbanimide A and

The aqueous oxa-Diels-Alder reaction has been successfully exploited in the synthesis of sesbanimides A and B [70], carbovir [71], mevinic acids [72], aris-teromycin and carbodine [73], ketodeoxyoctulosonic acid (KDO) and analogs... 

Such an aqueous hetero Diels-Alder reaction, which was extended to other dienes [42], was applied in various syntheses, including sesbanimides A and B [43], carbovir [44], mevinic acids [45], aristeromycin and carbodine [46], ketodeoxyoctu-losonic acid (KDO) and analogs [47], and sialic acids [48]. Pyruvaldehyde, glyoxal, and even ketones like pyruvic acid also react with dienes in water [42],... 

Senecio vernalis (senecivernine), 244 Sesbania drummodii seeds (sesbanimide A and sesbanimide B), 182 Sesbania punicea (sesbanimide A and sesbanimide B), 182 sponge Discodermia calyx (calyculin),... 

Powell, R. G., C. R. Smith, Jr., and D. Weisleder, Sesbanimide A and related tumor inhibitors from Sesbania drummondii Structure and chemistry. Phytochemistry, 23. 2789-2796... 

Sesbanimide A (34), together with its two stereoisomers sesbanimide B-l(35), sesbanimide B-2 (36) and sesbanimide C (37) all occur in Sesbania drunmondli, the structures rest on spectral and X-ray diffraction analyses. Each compound is strongly cytotoxic (R.C. Powell et al.,... 

On the other hand, diacetone D-glucose was transformed to (-)- and (+)-sesbanimide A via the open chain derivative 3-0-benzyl-D-glucose diethyldithioacetal 17, which was prepared by hydrolysis of 3-C -benzyl-l,2 5,6-di-C -isopropylidene-D-glucofuranose (16) and subsequent treatment with ethanethiol in the presence of acid (Scheme 3)4 Acetonation of 17 under kinetic control followed by methylenation with dibromomethane afforded the key intermediate 1,3-dioxane 18. Deprotection of the dithioacetal unit in 18 followed by... 

Alternatively, the readily accessible 1,2-0-isopropylidene-a-D-xylofuranose (41) was used for the total syntheses of the natural (-l-)-sesbanimide A (1) and the unnatural (-)-sesbanimide B (3) (Scheme Benzylation of 41 afforded 42 whose acetonide group... 

Treatment of 74 with 75 in the presence of borontrifluoride etherate followed by hydrolysis afforded 76 and 77. Swern oxidation of 77 gave 78, which on treatment with acetic acid afforded (-)-sesbanimide A (2) in 17% overall yield from the aldehyde 67. The analogue 80 was similarly prepared from 76, via compound 79. 

The antibiotic hydantocidin (72) has been made from D-fructose, with configurational inversion at C-3 by a redox sequence, and some acyclic O-methyl analogues of the antitumour agent sesbanimide A have been prepared from D-xylose by a route analogous to that used for sesbanimide itself (see Vol. 20, p. 265).56... 

Sesbanimide is a novel cytotoxic compound isolated from Sesbania puni-cea seeds [84JCS(P1)1311]. According to high-field H- and C-NMR spectroscopy, in solution a solvent-dependent equilibrium exists between the... 

The antitumour agent sesbanimide (64) has been a popular target. Extension of the D-xylose derivative (65) at C-1 (Scheme 14) gave the AB ring system (66), and use of L-xylose gave the enantiomer. Alternatively, extension of the related D-xylose derivative (67) at C-5 led ultimately to the AB ring system in the form of (68)... 

A number of unusual alkaloids have been isolated from the seeds of Sesbania drummondii (Fabaceae, coffee bean, rattle bush, or rattle box), a plant of the southeastern United States (Fig. 37.13) (Powell and Smith, 1981 Powell et al., 1976, 1984 Suffness and Cordell, 1985). Other species of this genus also appear to contain alkaloids. The seeds are poisonous to cattle, goats, and sheep. Although the alkaloid sesban-ine (43) occurred in small amounts and was isolated as a part of antitumor screens, the actual activity resided with an even more minor compound, sesbanimide (44), that was finally isolated in 5 X 10 % yield. Sesbanimide is the major cytotoxic and antileukemic compound in the plant. Two additional antitumor compounds have been isolated, sesbanimide B (45) and C (46) (Powell et al., 1984). 

The structure of sesbanimide is similar to that of the antibiotics cycloheximide (47), streptimidone (48), and strepto-vitacin A (49), but, so far, all evidence suggests that these alkaloids are plant products and not fungal metabolites (Suffness and Cordell, 1985). 

Last year saw the application of D-xylose to the synthesis of sesbanimide and this strategy has been extended to encompass ring C variants. A new synthesis of the cosmetic component 70 (a well-studied synthetic target that is derived from the civit cat) from 3,4-di-O-acetyl-L-rhamnal has been developed and the same group have described the use of L-rhamnal for synthesis of L-oleandrose 71. Methyl 6-deoxy-2,3-0-isopropylidene-a—D-mannopyranoside provides a flexible precursor to a series of deoxysugars (tetrahydropyrans), a-D-amicetoside 72, a-D-perosaminoside 73 and a-D-janoside 74.49... 

Some papers on nogalamycin congeners (see Vol. 19, p.257) are mentioned in Chapter 19 papers on sesbanimide are referred to in section 5, and a reference dealing with the epoxide leukotriene A4 is discussed with related systems in Section 6. 

A further synthesis of the bioactlve (+)-enantiomer (44) of sesbanimide has been reported, with the carbon framework of D-glucose being incorporated as shown, and a full account has been given of an alternative route to (44) and its (-)-enantiomer from the enantiomeric jqrloses (see Vol. 19, p.261, and V0I.2O. p.268).44... 

Michael Addition. The reaction of a, 8-unsaturated aldehydes andketones with trimethylsilylacetonitrile proceeds with 1,2- and 1,4-regioselectivity, respectively. A synthesis of (+)-sesbanimide highlights the utility of trimethylsilylacetonitrile in a Michael addition to an o(, -unsaturated ester lithiotrimethylacetonitrile gives exclusively the 1,4-addition product, whereas lithioacetonitrile gives mainly the 1,2-addition product. Desilylation of the former adduct results in the product of overall 1,4-addition of lithioacetonitrile. 

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