Ugi four component condensation using a polymer-bound carboxylic acid

Ugi four component condensation using a polymer-bound carboxylic acid 

The Ugi four component condensation (4CC) using 1-isocyanocyclohexene as a convertible isonitrile has already been mentioned in Chapter 3.2.3. In this paragraph we want to discuss the advantages of using one of the components linked to a solid support. 

The advantage of having the product linked to the solid support is obvious. Excess reagent drove the reaction to completion and could easily be removed by a washing procedure. The Ugi product 95 could subsequently be modified as discussed previously and then cleaved from the resin. 

Sequential Ugi-4CC and nza-Wittig reaction using a polymer-bound trapping reagent 

2) conversion of the azido group into an iminophosphorane ready for subsequent azsi-Wittig reaction and 

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