Oxetanocin transformation

Asymmetric [2 + 2] cycloaddition reaction affords a practical means of synthesis of optically active cyclobutanes, which can be used as useful intermediates in organic synthesis [138]. Narasaka reported that asymmetric [2 -i- 2] cycloaddition between acryloyl oxazolidinone derivatives and bis(methylthio)ethylene proceeded with high enantios-electivity when catalyzed by TADDOL-derived titanium complex (Sch. 58) [139]. The cyclobutane product was transformed into carbocyclic oxetanocin analogs or (-n)-grand-isol [140]... 

The synthesis of cyclobut-A (113), a nucleoside analogue of the potent antiviral antibiotic oxetanocin, was accomplished using intramolecular [2 + 2] cycloaddition catalysed by Cu(I) ions.711 An inseparable mixture of four (E, Z, syn, anti) isomers of 114 was obtained in 70% chemical yield by irradiation of a triene 115 (Scheme 6.48). The nucleoside connection was then established via nucleophilic substitution of an acetate group by adenine and other transformations in several steps. 

Figure 4.40 Structure of oxetanocin A 85 and its biological and chemical transformation to oxetanocins H, X, G, and 2-amino-oxetanocin A. Reagents i, adenosine deaminase or E. coli 120551 ii, Nocardia interfomur, iii (a) ACjO—EtjN (or 4-dimethylaminopyridine), acetonitrile, room temperature, 4 h and (b) 2,4,6-lriisopropylbenzensulfonyl chloride-EtjN (or 4-dimethylaminopyridtne), CHjClj, room temperature, 4 h iv, liquid NHj, EtOH, 110 °C, 3 days and v, adenosine deaminase.

Oxetanocin and its Analogues. - Fleet s group has synthesized oxetanocin (23) in a multistep procedure from D-glucose involving the transformation (21)— (22)(Scheme 1). ( )-Oxetanocin has been... 

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