Aproximacions a la síntesi estereoselectiva de noves heteroarilglicines

Abstract

L'objectiu principal de la present tesi doctoral ha consistit fonamentalment en la síntesi de noves heteroarilglicines òpticament pures. Amb aquesta idea s'han desenvolupat dues estratègies diferents: síntesi estereoselectiva utilitzant auxiliars quirals i síntesi estereocontrolada utilitzant aldehids quirals derivats d' L-serina com a "building-blocks". Així doncs, per a la primera estratègia s'han dissenyat i sintetitzat els dos nous auxiliars quirals del tipus imidazolidin-2-ona 111 i 135 utilitzant L-fenilalanina i L-serina respectivament com a materials de partida òpticament purs. Davant els problemes detectats en la síntesi d'a-aminoàdics mitjançant síntesi asimètric, s'ha canviat d'estratègia i s'ha utilitzat una síntesi estereocontrolada utilitzant aldehids quirals obtinguts a partir d'L-serina.

The main target of the present PHD work was the synthesis of optically pure novel heteroarylglycines. With this aim, two different strategies were developed: stereoselective synthesis using chiral auxiliaries, and stereocontrolled synthesis using chiral aldehydes derived from L-serine as "building-blocks". For the first strategy, two novel imidazolidine-2-one chiral auxiliaries of type 111 and 135 were designed and prepared. As optically pure starting materials, L-phenylalanine and L-serine were used respectively. Unfortunately, the stereoselective synthesis of a-aminoacids using these chiral auxiliaries did not afford the desired results, and, in almost all cases, unreacted starting material was recovered. In a second approach, an stereocontrolled synthesis using chiral aldehydes derived fom L-serine was developed.