Intramolecular amidoselenylation in the synthesis of unnatural amino acids

Abstract

In this paper use of intramolecular electrophilic amidoselenylation of unsaturated hydantoins for the construction of annulated bicyclic hydantoins, conformationally constrained precursors of substituted prolines is presented. In the case when alkenyl spirohydantoins were used as the substrates for amidoselenylation angularly fused tricyclic hydantoins are obtained. Reductive deselenylation and hydrolytic opening of the hydantoin ring of these products lead to fused bicyclic prolines, quaternary and constrained unnatural amino acids which can find application as peptidomimetics and also as intermediates in the synthesis of some natural products. Amidoselenylation of same substrates was also performed with in situ electrochemically generated selenium reagent. The reactions tolerate different substitutions at the unsatutated moiety and gave access to vide variety of derivatives.