Sphingosine derivatives

Figure 22.6 Sphingolipids are constructed of sphingosine derivatives containing an acylated fatty acid and a head group attached to the hydroxyl.

Glycolipids are carbohydrate-containing molecules, usually of sphingosine derivation, possessing a hydrophobic, fatty acid tail that embeds them into membrane bilayers. The hydrophilic... 

As shown in Scheme 3-30, a,/ -unsaturated aldehyde is treated with a-isocyanocarboxylate in the presence of gold complex (S)-(R)-82 to afford, after several steps, D-eryt/zro-sphingosine derivative.53b... 

Glycosylation of Trichloroacetimidates of D-Galactose with Sphingosine Derivative 6B... 

Endo K, Igarashi Y, Nisar M, Zhou QH, Hakomori S (1991) Cell membrane signaling as target in cancer therapy inhibitory effect of N,N-dimethyl and N,N,N-trimeth)d sphingosine derivatives on in vitro and in vivo growth of human tumor cells in nude mice. Cancer Res 51 1613-1618... 

More complex structures, often related to natural products are prepared by organic synthesis. Among them can be mentioned (f )-3-hydroxytetradecanoic acid (the double-tail hydrophobic moiety of lipid A), sphingosine derivatives related to the ceramides or 1,2- and l,3-dialkyl(acyl)glycerols related to glyco-glycerolipids, glycerophospholipids, and GPI anchors of membrane proteins. The preparations of the above derivatives were reported several years ago but some improvements have been published more recently. 

Gigg and Conant [47] have described the synthesis of the oxirane (49) as an intermediate for the synthesis of the protected sphingosine derivative (52). The oxazoline (1) was converted into the allyl furanoside (cf. 2) which gave the oxirane (49). The copper-catalysed Grignard reaction on (49) should give (50) which can be converted... 

Ceramides prepared in this way have been used for the partial synthesis of the a-L-fucopyranosyl ceramide (84) (a compound previously isolated from metastatic human carcinoma). Condensation [88] of 2,3,4-tri-Obenzyl-a-L-fucopyranosyl bromide (80) with an unprotected ceramide in the presence of tetraethylammonium bromide in di-chloromethane and subsequent chromatographic purification gave (81) which on catalytic hydrogenation gave the saturated fucosyl ceramide (84). The dichloroacetamido derivative (82) was prepared similarly and converted into the free sphingosine derivative (83) by the action of barium hydroxide. 

A sphingosine derivative, symbioramide (308), was obtained from the laboratory-cultured dinofagellate Symbiodinium sp. as a Ca2+-ATPase activator in the sarcoplasmic reticulum (250). The complete stereostructure of 308 was established by total synthesis (251). The occurrence of eo>f/iro-docosasphinga-4,8-dienine, as an ester (309), was found in Ammonia sulcata (252). This is the first example of a sphinga-4,8-dienine ester. A... 

Most glycolipids are glycosides with a sphingosine derivative (ceramide) acting as the aglycone. They are subdivided according to the nature of the carbohydrate residue (Table 1.8). 

Chirality transfer from the C—S bond of sulfoxide (189) to the C—O bond of the sphingosine derivative (190) gave a single isomer (equation 58). This type of chirality transfer will become more popular due to Whitesell s synthesis of suitable homochiral sulfoxides (equation 59). ... 

In 1995, sulfobacin A (158, Figure 6.19) and B (159), von Willebrand factor receptor antagonists, were isolated by Kamiyama et al. from the culture broth of a terrestrial bacterium Chryseobacterium sp. In the same year, the isolation of flavocristamide A (160) and B (=sulfobacin A, 158), DNA polymerase a inhibitors, from the cultured mycelium of marine bacterium Flavobacterium sp. in Hokkaido was reported by Kobayashi et al. These are sulfonolipid, and unusual sphingosine derivatives. We became interested in synthesizing these three sulfur-containing compounds, and carried out their synthesis from L-cysteine.23,24... 

The geometry of the double bond of sphingosine and of some natural sphingosine derivatives has been elucidated.9-11 The dia-stereoisomeric relationship of the amino and 3-hydroxyl groups is erythro this was proved by degradation and synthesis.12... 

In Table III are listed some of the synthetic sphingosine derivatives that do not exist in Nature. 

Two novel sphingosine-derived azetidine alkaloids, penaresidins 6, were isolated as potent actomyosin ATPase activators from the Okinawa marine sponge Penares sp.9... 

In glycerolipids and ether glycerolipids, glycerol serves as the backbone to which fatty acids and other substituents are attached. Sphingosine, derived from serine, provides the backbone for sphingolipids. 

The E2 reaction can also be applied to the synthesis of alkynes. When a vinyl halide is treated with a strong base, loss of HX by what is essentially an E2 process leads to formation of a triple bond. In a simple example, 12-methyltridec-l-ene was treated with bromine in dichloromethane to give dibromide 193. When this was treated with potassium tert-butoxide in petroleum ether, in the presence of 18-crown-6, initial elimination gave vinyl bromide 194 but this reacted again with the base, and an E2 reaction gave alkyne 195 in 72% yield for both chemical steps. Alkyne 195 was used in Mori s synthesis of the sphingosine derivative sulfobacin... 

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