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Efficient Preparation of [1‐ 15 N]‐3‐Cyano‐4‐methyl‐1 H ‐pyrrole by a Wittig‐Based Strategy
Author(s) -
Dawadi Prativa B. S.,
Lugtenburg Johan
Publication year - 2008
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200800079
Subject(s) - wittig reaction , chemistry , pyrrole , nitrile , aldehyde , yield (engineering) , phthalimide , organic chemistry , combinatorial chemistry , medicinal chemistry , catalysis , materials science , metallurgy
3‐Cyano‐4‐methyl‐1 H ‐pyrrole ( 1 ) was prepared by a new Wittig procedure from simple, commercially available starting materials in four steps with an overall yield of 39 %. Similarly, [1‐ 15 N]‐3‐cyano‐4‐methyl‐1 H ‐pyrrole ( 1a ) was prepared starting from [ 15 N]‐phthalimide. In this synthesis, Wittig coupling was used to form the central C–C bond of intermediate 6 , which has nitrile and methyl substituents. Upon deprotection and cyclization pyrrole 1 is obtained directly in one pot. This scheme also allows stable isotope incorporation at any position or a combination of positions. 3‐Cyano‐4‐methyl‐1 H ‐pyrrole was converted into the novel 1‐benzyl‐3‐cyano‐4‐methylpyrrole and the novel 4‐methyl‐1 H ‐pyrrole‐3‐aldehyde. It is clear that this novel Wittig procedure has a wide scope that will allow the easy preparation of many new pyrrole systems.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)