Diaminopropanoic acid residue

The C(l) to N(14) segment of the potent thrombin inhibitor cyclotheonamide A (109) was prepared from L-arginine, L-proline, and L-asparagine. The arginine backbone was extended via a cyanohydrin, and the unusual diaminopropanoic acid residue (184) was obtained from hypervalent iodine oxidation of the asparagine side chain [139] (Scheme 48). 

During the late stages of the asymmetric total synthesis of capreomycidine IB it was necessary to transform an asparagine residue into a diaminopropanoic acid residue." R.M. Williams et al. employed a chemoselective Hofmann rearrangement, thereby avoiding protection and deprotection steps that would have been necessary had the diaminopropanoic acid been introduced directly. The complex pentapeptide was treated with FIFA and pyridine in the presence of water to afford the primary amine in high yield. 

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