Ugi reaction for the synthesis of 4-aminopiperidine-4-carboxylic acid derivatives. Application to the synthesis of carfentanil and remifentanil

A two-step sequence involving an Ugi four-component reaction was developed for the preparation of 4-aminopiperidine-4-carboxylic acid derivatives. This strategy has led to the successful preparation of two drugs carfentanil and remifentanil in shorter times and better yields than previously described methods.