Adenosine, allyl

A C2 symmetric bis(amidophosphine) ligand was used by Trost to prepare the natural nucleoside adenosine (see Chapter 49 for nucleosides) in similar fashion to the carbocyclic analogue described above. The key enantioselective step was the first allylic alkylation that selected between two cnan-tiotopic benzoates in the meso dihydrofuran derivative to give one enantiomer the expected cis product. 

A photophysical study of the interaction of 2-amino-4,6-dimethylpyrimidine in p-CD has been carried out. Calculations have been carried out in an examination of the isomerism of methyl urocanate. Density functional theory techniques have been used to study the dimerization of thymine units in DNA. The effects of both low intensity irradiation (254 nm) or laser photolysis at 266 nm on adenosine have been reported. The photoionization of various purine and pyrimidine derivatives can be brought about by 266 nm nanosecond laser photolysis. Irradiation of alloxan in the presence of alkenes with allylic hydrogens affords adducts of 5-hydroxy-5-alkenyl barbituric acid. When the alkene is... 

Asymmetric synthesis of nucleoside has been carried out based on desym-metrization of the meso form of c/5 -2,5-dibenzoyloxy-2,5-dihydrofuran diester (210), which possesses two allylic leaving groups at 2,5-positions with correct stereochemistry. N-allylation of 6-chloropurine (211) with 210 using Pd(0)-(/ ,R)-Trost L-1 afforded 212. Reaction of 212 with a malonate derivative using PPh3 afforded 214, which was converted to adenosine 216. The enantiomeric adenosine 217 was prepared via 213 and 215 simply by using (5,5)-Trost L-1 in the first allylation [80]. 

The isopentenyl pyrophosphate is then obtained with adenosine triphosphate via a series of intermediary stages, and part is converted to dimethyl allyl pyrophosphatef ... 

Those of interest in the present context are short chain N -substituted adenosine analogues, namely, the allyl, -CH2 CH-CH2 isopropyl, -CH(CH3 >2 propargyl, -CH2 C=H and 2-(methylallyl), -CH2C(CH3)=CH2 [26]. All show cytotoxic effects in a number of in vitro and in vivo tumour cell systems. The authors state that an interesting finding was that these compounds had no cytotoxic effect on a leucocyte cell line in vitro which had originated from normal cells this observation was not pursued further by them. 

Raw garlic per se 5-glutamyl-5-allyl-L-cysteines, 5-allyl-L-cysteine sulfoxides, allicin, adenosine Intact clove with the white or pink skin by simple pull off Precursor of allicin, methiin, (-t-j-S-ftrani-l-propenyO-L-cysteine sulfoxide, and cycloalliin... 

There has been a further report on the preparation of 3 -deoxy-3 -C-allyl thymidine by free radical coupling (see also Vol. 23, p.2l8), and this has been converted into the AZT analogues (74) and (75). 126 xhe adenosine and 2 - deoxyadenosine derivatives corresponding to (75) have also been reported via a Wittig-reduction approach operating on a 3 -ketonucleoside.l27... 

A synthesis of 2 -0-methyluridine has been carried out by a procedure in which the 3, 5 -0-TIPDS derivative of uridine was protected at N-3 by the p-methoxybenzyl group,208 and the "wobble position" nucleoside 2 -0-methyl-5-(methoxycarboxylmethyl)uridine has also been prepared by similar means.209 The 2 -0-allyl derivative (141) of uridine is accessible by a palladium-catalysed decarboxylation of (142), and a similar reaction is possible on an adenosine derivative.210 2 -0-Propargyl uridine can be prepared via the 2, 3 -0-dibutylstannylene derivative the triple bond of this derivative could then be converted into an unusual carboranyl group, the resultant structure being of potential use in the neutron capture therapy of cancer.211 A conference report has discussed the use of 2-(methylthio)-phenylthiomethyl (MPTM) ethers for protection of the 2 -hydroxyl group in oligoribonucleotide synthesis.212... 

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