Nucleosides containing Amino-sugar Components

The antibiotic 2 -amino-2 -deoxyguanosine, 2 -amino-2 -deoxyadenosine, and 3 -amino-3-deoxy-jc /o-adenosine have been synthesized. 

2 -Amino-2 -deoxyarabinofuranosyl adenine has been synthesized via the aziridine (94) by reaction with ethyl trifluorothioloacetate it was found to be less active against murine leukaemia cells than the corresponding 2 -hydroxy compound. Opening of the anhydro-ring of 2,2 -anhydro-l-D-arabino-furanosyI-5-lluoroQrtosine with amines gave the 2 -substituted-amino-p- 

Ikehara and T. Maruyama, Chem. and Pharm. Bull. Japan), 1978, 26, 240. 

Reagents i, BUjSnO-DMF ii, TsCl-NEtj iii, DHP-H+ iv, Na-Hg v, NaH-CFaSO Cl Vi, MX-HMPA 

Similar reactions were performed on 2, 5 -0-ditrityluridine to give the 3 -azido- r /o-nucleoside (97) whereas 3, 5 -0-ditrityluridine afforded only 0 ,2 -cyclouridine.  

A general method for the preparation of (2-azido- and 2-amino-2-deoxy-D-ribo-furanosyl)purines has been described. Thus, condensation of l,3,5-tri-0-acetyl-2- 

The unsaturated isonucleoside (617), whose structure was established by X-ray crystallography, was obtained on fusion of the unsaturated sugar derivative (618) with theophylline in the presence of boron trifluoride etherate.  

The phosphoramidate analogues (619) of cAMP and improved syntheses of 5 -azido-5 -deoxythymidine and 5 -azido-2, 5 -dideoxyadenosine and their S -phosphates have been reported. 

Hydrogen sulphide in aqueous pyridine ean be used for the selective reduction of azido-groups on unsaturated sugar moieties of nucleosides.  

The daunosaminyl (3-amino-2,3,6-trideoxy-L-/) xo-hexopyranosyl) analogue of the antibiotic puromycin and -daunosaminyl derivatives of adenine, thymine, and cytosine have been synthesized. For example, 9-P-daunosaminyladenine was prepared by condensing 3-lV,4-0-bis(trifluoroacetyl)-a-daunosaminyl chloride with lV -benzoyl-9-chloromercuriadenine in refluxing xylene, or with IV -benz-oyladenine in dichloromethane at room temperature in the presence of a molecular sieve, and removal of the protecting groups from the product. 

Treatment of 9-(2,3-anhydro-jS-D-lyxofuranosyl)adenine with azide ion, followed by inversion of the configuration of the neighbouring trans-hydroxy-group in the products, has been used to obtain 2 -azido-2 -deoxy- and 3 -azido-3 -deoxy-adenosine.  

Reagents i, LisOaPS ii, l-ethyl-3-(3-dimethylaminopropyl)carbodi-imide 

Carbocyclic puromycin was synthesized from (488) by inversion of the configuration at C-2 after the purine base had been formed. 

---

Amino sugars are components of antibiotic substances109 and bacterial polysaccharides,1,0 and are therefore of interest. The nucleoside antibiotics amicetin, bamicetin, and plicacetin contain, as the sugar residue, a monoaminopentadeoxy disaccharide that is closely related to maltose. In view of the reported antibiotic and antitumor properties of these pyrimidine nucleosides,111,112 the synthesis of aminodeoxy derivatives of maltose would be of interest. 

The nucleosides (261) and (371) (analogues of gougerotin) were obtained from branched-chain amino-sugars described in Chapter 15. The assignment of configuration at the branch-point of nucleosides containing a saccharinic acid component is reported in a later section (see p. 156). 

---