Hippuric acid, transformation into

Gly-OEt was also added to ethyl 3-perfluoroalkylpropynoates which were transformed in several steps into 5-perfluoroalkyl-substituted l-methyl-2-ethoxycarbonylpyrrolidin-3-ones (90X6705). 3-Propyl- and 4-propylpro-lines and 4- -pentylproline were synthesized from diethyl acetamidomalo-nate and an unsaturated aldehyde (67JA2459 72JMC1255). Ethyl benzyli-denecyanoacetate reacts with hippuric acid to give the pyrrole 8 (87H2323). 

Three synthetic approaches for benzopyrones have been developed that use Gly as starting material. Hippuric acid was transformed with acetic anhydride into 2-phenyl-5(4//)oxazolone or further into its 4-ethoxy-methylene derivative, then reacted with cyclic 1,3-dicarbonyI compounds (such as like dimedone) to form 100 [90LA501 92H(33)843]. On the other hand, when hippuric acid was transformed into methyl 2-benzoyl-amino-3-dimethylaminopropenoate, it reacted with resorcinol to give a 7-hydroxybenzopyrone derivative (89JHC1273). 

When treated with the reaction product of hippuric acid and DMF-DMA, 3-aminopyridazine was transformed into a derivative of the pyridazino-pyrimidine system 117. The same result was achieved when 3-aminopyridazine was reacted first with DMF-DMA and thereafter with the protected cyclic glycine derivative (88H903 90JHC359). 

Two syntheses of cyclopenin have been fully described. " One involved the preparation of a penultimate intermediate (21) as a mixture of two double bond isomers which were separated and transformed by epoxidation with meta-chloroperbenzoic acid into cyclopenin (18) and isocyclopenin respectively. In the other, the same intermediate (21) was prepared by two stereospecific routes starting with hippuric acid derivatives (23)." The Erlenmeyer synthesis on (23) produced the ester (22) which gave the benzodiazepine (21) in two steps. An extension of this approach led to the synthesis of cyclopenol [(18), m-HOC6H4 for Ph]. 

---