Synthesis of homochiral amino acid pyrazine and pyrrole analogues of glutamate antagonists

摘要

Use of the acid 7 and the aldehydes 23a and 23b in “ring switching” reactions with hydrazines has givennβ-(1-aminopyrrole)amino acids as kinetic products. The products from the reaction of the aldehyde have beennconverted into β-(pyrazine)amino acids by an equilibration–dehydration sequence. A variety of homochiralnreduced heterocyclic amino acids containing two chiral centres has been prepared in this way. Some of thenproduct amino acids undergo “reverse ring switching” to the corresponding pyroglutamic acid derivatives.