Pyrrylmagnesium bromide

A classical method for preparing C-acylated pyrroles involves the acylation of pyrrylmagnesium bromide. In general, tightly coordinated TV-pyrryl and indolyl salts, exemplified by their Grignard derivatives, undergo preferential C-acylation and C-alkylation (Scheme 3) (81TL4647). 

Treatment of 2,3,6,7-tetramethoxy-3-chloromethylphenanthrene with pyrrylmagnesium bromide yielded the pyrrole derivative (192), which was reduced to the corresponding... 

Alkylation of N-heteroeycKc compoumb. Pyrrole can be N-alkylated sali ractorily by conversion to pyrrylthallium(I) by reaction with thallous ethoxide. This is a relatively stable solid the structure is uncertain. Reaction of this salt with an excess of an alkyl halide (or an alkyl tosylate) for 1-32 hr. at 20-60° gives N-alkylpyrroles in good yield. Alkylation of pyrrylmagnesium bromide gives isomeric 2- and 3-alkylpyrroles as the major products. 

The hitherto undetermined question whether the side chain, attached to the pyrrolidine ring in hygrine, is — CH COCHj or — COCH2CH3 was settled by the synthesis of these two bases by Hess (18). The required starting material for the synthesis of hygrine was obtained as a product of the reaction of a-pyrrylmagnesium bromide with propylene oxide. The main product, (VI), of the reaction when treated with water yielded... 

---