3-Lithiopyrroles by Halogen-Metal Interchange of 3-Bromo-1-(triisopropylsilyl)pyrroles. Synthesis of Verrucarin E and Other 3-Substituted Pyrroles.

Article abstract of DOI:10.1002/hlca.19840670430

3-Lithio-1-(trimethylsilyl)pyrrole (7, Scheme 2), obtained by halogen-metal interchange from the 3-bromo compound 2, reacted with various electrophilic reagents to provide products, which on fluoride ion desilylation, gave 3-substituted pyrroles in good overall yields.One such pyrrole 13 (Scheme 3), was converted into 2-formyl-3-octadecylpyrrole (14), reputed to be a metabolite of the marine sponge Oscarella lobularis. 3,4-Dibromo-1-(triisopropylsilyl)pyrrole (5) was efficiently transformed, by a process involving two conscutive bromine-lithium exchange reactions (Scheme 4), into the antibiotic verrucarin E 17.