Synthesis of N-protected 2-hydroxymethylpyrroles and transformation into acyclic oligomers

Article abstract of DOI:10.1055/s-1996-4308

The synthesis of N-tosylated and N-Boc-protected 2-hydroxymethyl-pyrroles 2a-c and 3a-d and their transformation into di- and tripyrroles 18, 20a and 20b as well as the preparation of the vinyl- and ethynylpyrroles 13a, 13b and 15 is described. The pyrrole-2-carboxylic acid ethyl esters 7a and b and the pyrrole-2-carbaldehydes 4a-d were transformed into their N-protected derivatives 5a, 5b, 6a-d, 8a and 8b in 69-97% yield and reduced to give the corresponding hydroxymethylpyrroles 2a-c and 3a-d in 79-96% yield; treatment of 2b with 17, 19a and 19b in 0.5% hydrochloric acid gives the dipyrrole 18 and the tripyrroles 20a and 20b in 20-28% yield.