Erlenmeyer-Plochl

Formation of 5-oxazolones (or azlactones ) (2) by intramolecular condensation of acylglycines (1) in the presence of acetic anhydride is known as the Erlenmeyer-Plochl azlactone synthesis. ... 

The azlactones of a-benzoylaminocinnamic acids have traditionally been prepared by the action of hippuric acid (1, Ri = Ph) and acetic anhydride upon aromatic aldehydes, usually in the presence of sodium acetate. The formation of the oxazolone (2) in Erlenmeyer-Plochl synthesis is supported by good evidence. The method is a way to important intermediate products used in the synthesis of a-amino acids, peptides and related compounds. The aldol condensation reaction of azlactones (2) with carbonyl compounds is often followed by hydrolysis to provide unsaturated a-acylamino acid (4). Reduction yields the corresponding amino acid (6), while drastic hydrolysis gives the a-0X0 acid (5). ... 

Kirk and coworkers recently reported preparation of 6-flouro-meta-tyrosine 29 based on an Erlenmeyer-Plochl azlactone strategy from 2-benzyloxy-5-fluorobenzaldehyde. 

A variant of the Perkin reaction is the Erlenmeyer-Plochl-azlactone synthesis By condensation of an aromatic aldehyde 1 with an N-acyl glycine 5 in the presence of sodium acetate and acetic anhydride, an azlactone 6 is obtained via the following mechanism ... 

Erlenmeyer, E., Jr. Ann. 1893, 275, 1. Emil Erlenmeyer, Jr. (1864—1921) was bom in Heidelberg, Germany to Emil Erlenmeyer (1825—1909), a famous chemistry professor at the University of Heidelberg. He investigated the Erlenmeyer-Plochl azlactone synthesis while he was a Professor of Chemistry at Strasburg. 

Brooks, D. A. Erlenmeyer—Plochl Azlactone Synthesis in Name Reactions in Heterocyclic Chemistry, Li, J. J. Corey, E. J., Eds. Wiley Sons Hoboken, NJ, 2005, 229-233. (Review). 

Attempts to synthesize ATrp derivatives by the well-known Erlenmeyer-Plochl method using an azlactone result in very poor yields.However, using an altogether different strategy Moriya et alJ143l synthesized ATrp derivatives with Z configuration in much better yields. In this method condensation of 3-(aminomethylene)-3//-indole 53 with A-acylglycine esters 54 was used to synthesize A-acyl-substituted ATrp derivatives 55 (Scheme 18). 

ERLENMEYER - PLOCHL - BERGMANN Amino Acid Synthesis... 

Erlenmeyer-Plochl azlactone and amino acid synthesis. Formation of azlactones by intramolecular condensation of acylglycines in the presence of acetic anhydride. The reaction of azlactones with carbonyl compounds followed by hydrolysis to the unsaturated a-acylamino acid and by reduction yields the amino acid drastic hydrolysis gives the a-oxo acid. 

This reaction is related to the Erlenmeyer-Plochl Azlactone Synthesis. 

The starting material for the enantioselective hydrogenation is obtained very elegantly by an Erlenmeyer-Plochl reaction ofvaniUm, N-acetylglycine and acetic anhydride. The azlactone is carefuUy hydrolysed with water and the enamide purified by crystallisation. 

In contrast to the Monsanto process, it was decided to use hippuric acid in the Erlenmeyer-Plochl condensation for the VEB ISIS-Chemie Zwickau procedure. 

Erdmann (see Volhard-Erdmann Cyclization) Erlenmeyer-Plochl Azlactone and Amino Acid Synthesis Eschenmoser Coupling Reaction Eschenmoser Fragmentation Eschenmoser-Claisen Rearrangement Eschenmoser-Tanabe Fragmentation Eschweiler-Clarke Reaction Etard Reaction... 

He investigated the Erlenmeyer-Plochl azlactone synthesis while he was a Professor of Chemistry at Strasburg. The Erlenmeyer flasks are ubiquitous in organic chemistry laboratories. 

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