Brønsted acid catalyzed azlactone ring opening by nucleophiles
作者:Adriane A. Pereira、Pedro P. de Castro、Amanda C. de Mello、Bruno R.V. Ferreira、Marcos N. Eberlin、Giovanni W. Amarante
DOI:10.1016/j.tet.2013.11.037
日期:2014.5
Brønsted acid catalyzed azlactone ringopening in the presence of different nucleophiles leading to the efficientsynthesis of protected amides and amino esters is presented. Sixteen compounds were synthesized in good to excellent isolated yields. Mechanism investigation by using ESI(+)-MS/MS revealed that the CSA catalyst promotes azlactone activation for electrophilic attack facilitating therefore
Hydro-De-Phosphoniation of 4-Substituted-4-Triphenylphosphonio-5(4<i>H</i>)-Oxazolones With Alcohols
作者:Roman Mazurkiewicz、Anna W Pierwocha、Anna Brachaczek、Iwona Mitrus
DOI:10.1080/10426500008076324
日期:2000.2
Abstract 4-Substituted-4-triphenylphosphonro-5(4H)-oxazolones with a bulky alkyl substituent at the position 4 treated with MeOH in the presence of DBU (1.8-diazobicyclo[5.4.0]undec-7-ene) at room temperature give corresponding N-acyl-α-amino acid esters. In the case of a smaller substituent at the position 4 (Me, MeOCH2), the triphenylphosphonium group was competitively displaced by the methoxy group