Homogeneous Polymer-Supported Synthesis of N-Substituted Pyrroles

Significance

An efficient and general route to soluble polymer-assisted synthesis of N-substituted pyrroles using dendritic polyglycerol was achieved. Thus, 3-(2,5-dihydro-2,5-dimethoxy­furan-2-yl)pyropanoic acid polyglycerol ester (2) was prepared according to reported procedures (Angew. Chem. Int. Ed. 2004, 43, 2297-2299). The transformation of 2,5-dihydrofuran 2 to tetra­hydrofuran 3 was performed via catalytic hydro­genation with Pt/C. Paal-Knorr-type condensation of 3 with primary amines followed by the cleavage of the polyglycerol with LiOH gave the corresponding pyrroles 5 in 50-65% yields.