Other Derivatives

The 2 -0-(2-nitrobenzyl) derivatives of adenosine and cytidine, which are normally prepared using 2-nitrophenyldiazomethane and tin(ii) chloride (see Vol. 9, p. 163), have now been prepared using 2-nitrobenzyl bromide and sodium hydride in DMF. These ethers are of interest because they are readily removed by photolysis in methanol-DMF. 

Adenosine, as a 2 1 mixture of the R - and (S) isomers, has been synthesized from D-[5- H]xylose. The observed spin-spin coupling between the residual 5 -protons and H-4 showed that the gauche-gauche rotamer is preponderant (ca. 70%) and the gauche-trans rotamer of minor importance (ca. 20%) in aqueous solution, contrasting with the preference for the latter rotamer exhibited by adenosine in the solid state. Degradative studies have established that naturally 

The benzodioxanyl derivatives (628) and (629) were formed when adenosine or uridine, respectively, reacted briefly with 2-acetoxybenzoyl chloride in liquid sulphur dioxide at or below —15 °C. On prolonged reaction, followed by methanolysis, adenosine gave the 2, 3 -acetal (630) and 9-(3-chloro-3-deoxy-p-D-xylofuranosyOadenine.  

Holy and H. Pischel, Coll. Czech. Chem. Comm., 1977,42, 2261. 

The use of iron(iii) chloride to catalyse the acetonation of ribonucleosides is mentioned in Chapter 5. 

Some other cinchona alkaloid derivatives that have been synthesized and were evaluated as chiral selectors for liquid chromatographic enantiomer separation comprise CSPs based on cinchonan hydrazides [68], cinchonan ureas [42], cin-chonan amides [42], and urea-linked cinchonan-calixarene hybrid selectors [42] 

Carbamate-linked (epi) Quinine-calixarene Hybrid-type CSPs 

FIGURE 1.12 CSPs on the basis carbamate and urea-linked cinchonan-calixarene hybrid selectors as examples for CSPs with complementary enantioselectivity profiles. (Reproduced from K.H. Krawinkler et al., J. Chromatogr. A, 1053 119 (2004). With permission.) 

It is also worthwhile to outline at this place the immobilization procedure that was used for the preparation of type I CSPs A bifunctional linker with a terminal isocyanate on one side and a triethoxysilyl group on the other end (3-isocyanatopropyl triethoxysilane) was reacted with the native cinchona alkaloids quinine and quinidine and subsequently the resultant carbamate derivative in a second step with silica [30], Remaining silanols have been capped with silane reagents, yet, are less detrimental for acidic solutes because of the repulsive nature of such electrostatic interactions. CSPs prepared in such a way lack the hydrophobic basic layer of the thiol-silica-based CSPs mentioned earlier, which may be advantageous for the separation of certain analytes. 

A copolymerization approach of 0-9-[2-(methacryloyloxy)ethylcarbamoyl] cinchonine and cinchonidine with methacryl-modified aminopropylsilica particles was utilized by Lee et al. [71] for the immobilization of the cinchona alkaloid-derived selectors onto silica gel. The CSPs synthesized by this copolymerization procedure exhibited merely a moderate enantiomer separation capability and only toward a few racemates (probably because they were based on less stereodifferentiating cinchonine and cinchonidine). Moreover, the chromatographic efficiencies of these polymer-type CSPs were also disappointing. 

Adenosine reacted with trimethyl or triethyl orthoformate in the presence of trichloroacetic acid to give only eam-2, 3 -0-alkoxymethylene derivatives (496), which were isolated in yields of 55% and 82%, respectively. Carbonyldi-imidazole has been used in the synthesis of uridine and 6-azauridine 2, 3 -car-bonates. Phosphorylation and alkaline hydrolysis of the acetals (497) (pre- 

Partial methylation of 9-jS-D-arabinofuranosyladenine with dimethyl sulphate yielded a mixture of mono-, di-, and tri-O-methyl derivatives- 5 -0-Methyl-adenosine was found to resist enzymic deamination. Syntheses of 5 -0-acyl and 

A -alkyl derivatives of tubercidin and of 9-(6-deoxy-6-nitro-j8-D-glucopyrano-syl)adenine have been reported. Guanosine reacted with tetrakis(hydroxy-methyl)phosphonium chloride to give the JV -substituted phosphine (499). The preparation and properties of osmium-ligand complexes of nucleosides are mentioned in Chapter 18.  

Darzynkiewicz, Z. Kazimierczuk, and D. Shugar, Cancer Biochem. Biophys., 1976, 1, 203 Chem. Abs., 1976, 85. 160 456n). 

Berinek and H. Hrebabecky, Nucleic Acids Res., Special Publ., 1975, 1 (3rd Symposium Chem. Nucleic Acids Components, 1975), S57 Chem. Abs., 1976, 85, 63 274t). 

In complete analogy to silicon, trialkyltin chlorides react with the lithiated ferrocenylalkyl amines to give the corresponding tin derivatives (Fig. 4-26, bottom) trimethyltin [129] and tributyltin substituents [106] have been introduced by this method. The tin compounds are more reactive towards transmetalation than the silicon analogues and are therefore useful intermediates in the preparation of other derivatives [129], e.g., by C —C coupling to give chiral biferrocenes [106]. Several racemic planar chiral derivatives of ferrocenyltriethylstannane have been prepared via lithiated N,lV-dimethyl-ferrocenylmethylamine and similar compounds [150]. 

Many other electrophiles are able to react with metalated ferrocenylalkyl amines, e.g., trimethyl borate (Fig. 4-27 a), which gives, after hydrolytic workup, compounds like (S,S)-l-(iV,iV-dimethyl-l-aminoethyl)ferrocene-2-boronic acid [106]. Important intermediates for further derivatization are the halogens. For the lithiation technique, I2 (Fig. 4-27b) [151] and BrCN [106] lead to the desired compounds, but when BrCN is used, partial substitution of the dimethylamino group by cyanide occurs (see Sect. 4.3.3.2 and Fig. 4-17). For palladated amines, Brj is applicable [152]. (i ,S)-l-Iodo-2-(iV,iV-dimethyl-l-aminoethyl)ferrocene is the starting material for catalytically active zinc compounds for the enantioselective addition of zinc alkyls to carbonyl compounds [151] (see Chapter 3 for this topic). 

Among the carbon electrophiles, carbonyl compounds [113,114] were first applied in the reaction with lithiated ferrocenylalkyl amines (Sect. 4.S.3.3 and Fig. 4-18). Analogously, carboxylic acids are obtained from CO2 [153]. The reactivity pattern of palladated ferrocenylalkyl amines with carbon electrophiles is somewhat different. Carbon monoxide in alcohols leads to the formation of esters of substituted ferrocenecarboxylic acids [124]. With prochiral alcohols, a moderate asymmetric induction is observed [154]. a, -Unsaturated ketones react with palladated ferrocenylalkyl amines not with addition to the carbonyl group, but with substitution of a hydrogen at the carbon—carbon double bond, allowing the introduction of longer side chains at the ferrocene ring (Fig. 4-27c) [124, 152]. 

Note the P-helical conformation at the metallocene and the intramolecular hydrogen bond. (Reprinted from [39], with permission from The Royal Society of Chemistry). 

Both primary and secondary ammo acids react with 9-fluorenylmethyl chloroformate (FMOC chlonde) under alkaline, aqueous conditions (Anson-Moye and Boning, 1979). The reaction is complete in 30 s. However, although FMOC chloride is fluorescent, the excess reagent and the byproducts are easily removed by extraction prior to separation (Ejnarsson et al., 1983). 

The kinetics of the alkyl-halide-promoted phosphazene - phosphor-amide rearrangement  

The rearrangement follows first-order (in the phosphazene) kinetics and the rate increases as the electron density supplied by the substituents A and B increases. It was suggested that the reaction proceeds via a six-membered transition state such as (30). 

Mention has already been made of the aminophosphine - phosphazene rearrangement (Section 2). It has been noted that some of these phos-phazenes, (31) and (32) [Y = SOj-CFs, SOj-CeHi-p-Me, P(0)Ph2, P(S)Ph2, or PS(OPh)2], exhibit significant differences in the magnitude 

Interesting cyclic ionic species are obtained from the reactions of di(phosphazenyl)silanes with silicon halides at room temperature  

The same products were obtained from the reactions of certain Y-silyl-monophosphazenes with organosilicon dihalides  

Et3SiH (PhCO R3SiH, cat RSH (MejSi)jSiH, AIBN 

An analogue of adenosylhomocysteine, 5 -deoxy-5 -isobutylthio-3-deaza-adenosine, has been prepared and its biological and biochemical properties 

Reaction of adenosine with triphenylphosphine and diethyl azodicarboxylate gave the 2, 3 -phosphorane (105) and not the 3, 5 -phosphorane as previously reported (Mitsunobu et ai, Chem. letters, 1974, 1473). The structure was confirmed from H and P n.m.r. measurements. With aradmo-adenosine the 2, 3 -/yxo-epoxide (106) was obtained in near quantitative yield xylo-adenosine also gave (106) but much more slowly and in only 60% yield.  

A new class of bridged pyrimidine nucleosides has been obtained by the action of diazomethane on the cyclic keto-nucleoside (107) in methanol a mixture of the cyclonucleosides (108) and (109) was obtained. Some conversions of (108) were discussed.  

Purine nucleoside analogues with thiazolidine ring systems replacing the sugar have been made.  

4 -Thiocordycepin has been synthesized. 4 -Thio-D-er //r/ o-furanosyl nucleosides (110) have been prepared by reaction of the corresponding 4-thio-erythrose-2,3-phenylboronate with purine derivatives in the presence of p-toluenesulphonic acid or with silylated pyrimidines in the presence of tin(iv) 

The 2 -0-(l-methoxyethyl) ethers of nucleoside 5 -phosphates have been prepared either by phosphorylation of the corresponding nucleoside 2 -ether or by methoxyethylation of the nucleoside 5 -phosphates. Mixtures of the photo-labile 2 - and 3 -0-(2-nitrobenzyl)-ribonucleosides were obtained in good yields when adenosine, inosine, cytidine, and uridine were treated with 2-nitrophenyl- 

The reaction of some 7-hexopyranosyltheophylline nucleosides with benz-aldehyde in the presence of zinc chloride gave the expected benzylidene acetals with the a-D-mannopyranosyl (2, 3 4, 6 -diacetal), /S-o-galactopyranosyl (4, 6 acetal), and j8-D-glucopyranosyl (4, 6 -acetal) derivatives.  

A study has been made of the selective acylation of cytidine and 2 -deoxy- 

Crystal structures, mass and n.m.r. spectra were for the monomeric [n-CMcgSi)gCgHg]Li.L (L quinuclidine TMED or PMDT). 

Coversion of HgC=CH(CHg) M to CHg(CHg)2CHCHgM is faster for M=Lithan for R=MgX but is still 10 -10 times slower than cycl-ization of CHg=CH(CHg) . The mere observation of cyclopentylmethyl products in reactions of CHg=CH(CHg) X is not sufficient evidence for a radical process. However the reaction of Bu Li with CH2=CH(CHg)gCHRBr (R-H or Me) at low T does produce stable cyclized and uncyclized organolitbiums as well as cyclized hydro- 

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These are unstable and known only in solution. The ethyl glucosides can be obtained crystalline and other derivatives are known. 

PPha, pyridine) organic groups (olefines, aromatic derivatives) and also form other derivatives, e.g. halides, hydrides, sulphides, metal cluster compounds Compounds containing clusters of metal atoms linked together by covalent (or co-ordinate) bands, metaldehyde, (C2H40) ( = 4 or 6). A solid crystalline substance, sublimes without melting at I12 1I5" C stable when pure it is readily formed when elhanal is left in the presence of a catalyst at low temperatures, but has unpredictable stability and will revert to the monomer, ft is used for slug control and as a fuel. 

In general, nitro-hydrocarbons are most readily identified by reduction to the corresponding amine (above), which is then identified as its benzoyl or other derivative (p. 374). (M.ps., pp. 550-551.)... 

B.P. Alkylldene Dlmedone (I) Dimedone "Anhydride" (M) 2 4-Dinltn>-phenyl-hydnzone Seml- earbazone />-NItro- phenyl- hydrazone Other Derivatives Cd ss... 

Ketone B.P. M.P. 2 4-DlnltrO phenyi-hydrazone Semiear- bazone Benzal Derivative Phenyl- hydrazone />-Nltro- phenyU hydrazone Other Derivatives... 

Alcohol B.P. Benzoate />-Nltro- benzoate 3 S-Dinltro- benzoate Phenyl- urethane a-Naphtbyl- urethane Other Derivatives... 

Carbohydrate M.P. Time of M.P. Formation (Minutes) Other Derivatives... 

Hydrocarbon B.P. M.P. 20- 4 20 Picrate Aroyl- benzolc Acid Compound with 1 3 5-Trlnltro-benzene Styphnate Other Derivatives... 

Bento amide Benzene- sulphon- amide p-Tolu- enesul- phon- amide Plcrate Formyl Derivative Other Derivatives... 

Amine BJ>. M.P. Methlodide PIcrate Methyl p-toluene- sulphonate Other Derivatives... 

Semi- carbazone Oxime Hydro- quinone DIacetate of hydro-quinone Thiele acetylation product Other Derivatives... 

Acid B.P. H.P. AnlUde p-Tolu4- dide 1 Amide p-Bromo- phenacyl ter p-Nitro- benzyl Ester p-Phenyl phenacyl Ester S-Benzyl- uo-thi- uronium Salt Other Derivatives... 

Alcohol B.P. M.P, 3 5-Dinitro-benzoate p-Nilro- bemoate Phenyl- urethane a-Naph- thyl- urethane Hydrogen 3-nitro- phthalate other Derivatives... 

Aminothiazole itself (104a), R, = R2 = H (an intermediate in the preparation of sulfathiazole), was synthetized as early as 1888 from a,p-dihalogenoethylethers, which give chloroacetaldehyde in addic medium (8). Many other derivatives have now been used for this synthesis, and they are listed in Table IT12. All give excellent yields. 

These units are formed by combining base units, supplementary units, and other derived units (2—4). Those derived units having special names and symbols are marked with an asterisk in the Hst below. 

The higher members of the series decrease the surface tension of aqueous solutions well below the point possible with any type of hydrocarbon surfactant, although in practice because of their strong acid character and solubiUty characteristics, more commonly salts and other derivatives are employed. A 0.1% solution of C F COOH has a surface tension of only 19 mN/m (dyn/cm) at 30°C (6). 

Benzotrifluoride Derivatives. Laboratory recipes for 45 ben2otfifluorides have been pubhshed (322). Physical properties and toxicity of commercially significant ben2otfifluoride derivatives are fisted in Table 9 the amino compounds are colorless to yellow and other derivatives are colorless. 

The dichloride of molybdenum(II) [13478-17-6] M0CI2, contains Mo CF g core units (Fig. 6c) having chloride bridges in its soHd-state stmcture. Similar or identical hexanuclear units are known in soluble species such as Mo3Ch 24 other derivatives containing the Mo CF g core. These compounds have been under investigation because of their photochemical and photoluminescent activity (see Photochemical technology) (36,37). The hexanuclear... 

Naphthenic acids have been the topic of numerous studies extending over many years. Originally recovered from the petroleum distillates to minimise corrosion of refinery equipment, they have found wide use as articles of commerce in metal naphthenates and other derivatives. A comprehensive overview of the uses of naphthenic acid and its derivatives can be found in References 1 and 2. A review of the extensive research on carboxyUc acids in petroleum conducted up to 1955 is available (3), as is a more recent review of purification, identification, and uses of naphthenic acid (4). 

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