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Stereoselective Synthesis of (2 E ,4 Z )‐Dienamides Employing (Triphenylphosphoranylidene)ketene
Author(s) -
Pachali Steffen,
Hofmann Christine,
Rapp Georg,
Schobert Rainer,
Baro Angelika,
Frey Wolfgang,
Laschat Sabine
Publication year - 2009
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.200900176
Subject(s) - chemistry , ylide , wittig reaction , ketene , phosphonium salt , phosphonium , deprotonation , stereoselectivity , medicinal chemistry , orthoester , organic chemistry , hydrochloride , salt (chemistry) , catalysis , ion
The three‐component reaction between ylide Ph 3 PCCO, amines and aldehydes is known to afford selectively ( E )‐α,β‐unsaturated amides. We applied a variant of this methodology to the preparation of (2 E ,4 Z )‐dienamides 11 utilizing the phosphonium salt formation from ethyl 5‐aminopentanoate hydrochloride and Ph 3 PCCO followed by deprotonation with DBU and a Wittig olefination of the corresponding ylide with various ( Z )‐α,β‐unsaturated aldehydes 10 . The (2 E ,4 Z )‐dienamides 11 were isolated in yields of up to 80 %. The ( Z )‐configuration of the starting aldehydes 10 remained untouched during the reaction.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)