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New Efficient, Flexible and Regioselective Synthesis of 2,4‐Di‐ and 2,3,4‐Trialkylated an Arylated 1 H ‐Pyrroles
Author(s) -
Enders Dieter,
Maaßen Ralf,
Han SinHo
Publication year - 1996
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199619961011
Subject(s) - umpolung , chemistry , regioselectivity , yield (engineering) , aldehyde , silylation , alkyl , enol , aryl , medicinal chemistry , organic chemistry , combinatorial chemistry , catalysis , nucleophile , materials science , metallurgy
Starting from easily available 2‐acetoxy aldehyde dimethylhydrazones rac ‐ 2 , we prepared various alkyl‐ and aryl‐substituted 1 H ‐pyrroles 6 in good overall yield. The titariummediated a 2 ‐umpolung reaction of rac ‐ 2 with different acyclic and cyclic silyl enol ethers 3 leads directly or via 4‐oxo hydrazones rac,anti ‐ 4 to 1‐(dimethylamino)‐1 H ‐pyrroles 5 . A novel method for the reductive removal of the dimethylamino group affording 1 H ‐pyrroles 6 is presented.