Carbamoylpolyoxamic acid

Antifungal antibiotic (+ )-polyoxin J can be obtained in 46,4% yield by combining the derivative of 5-O-carbamoylpolyoxamic acid (348) with thymine polyoxin C (347) (Scheme 2.152) (196, 583)... 

Further, convenient syntheses of the two fragments of Polyoxin J, deoxypolyoxin C and 5-0-carbamoylpolyoxamic acid, have been achieved in a highly stereoselective manner starting from the same chiral building block, 4-0-benzyl-2,3-0-isopropylidene-L-threose, leading to a formal total synthesis of Polyoxin J (36). 

The synthesis of (-t-)-polyoxin J 14 is completed by selective ester hydrolysis with aqueous lithium hydroxide. The resulting carbamoylpolyoxamic acid was then coupled with the protected thymine polyoxin C 8 with the BOP reagent (Castro s reagent)14 (benzotriazol-1 -yloxytris(dimethyl-amino)phosphonium hexafluoro-phosphate) 37 to furnish the peptide derivative in 63 % yield. 

Figure 4.7 Early and latest biosynthetic pathways to carbamoylpolyoxamic acid (CPOAA).

Figure 4.8 Assembling of polyoximic acid and carbamoylpolyoxamic acid to the nucleoside skeleton to give polyoxin.

O-Carbamoylpolyoxamic acid, A-469 Carbocyclic 8-azaadenosine, A-452 Carbocyclic cytidine, C-13... 

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