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. Can. J. Chem. 60,2295Chem. 60, (1982. Several syntheses of the previously unknown 1,2-dihydro-3H-pyrrolo[l,2-a]pyrrole-l-carboxylic acid and various 5-and 6-substituted derivatives thereof have been devised. Some of these processes have been extended to the heretofore unreported 5,6,7,8-tetrahydropyrrolo[l,2-a]pyridine-8-carboxylic acid and 5,6,7,8-tetrahydro-9H-pyrrolo[l,2-a]azepine-9-carboxylic acid derivatives.Two new processes were developed for the conversion of pyrroles into the corresponding pyrrol-2-acetic acid esters. Both processes were based on the use of the readily available ethoxalylpyrrole derivatives as the starting material. One sequence involved saponification of the a-keto ester, followed by Wolff-Kishner reduction of the crude a-keto acid salt and subsequent esterification of the acetic acid derivative thus produced. The second synthesis commenced with reduction of the 2-ethoxalpyrrole with sodium borohydride to the a-hydroxy ester, which was further reduced to the acetic acid ester with an equimolar mixture of triphenylphosphine and triphenylphosphine diiodide.

A high incidence of tumor regression was observed in guinea pigs bearing transplantable, line-10 hepatocellular carcinomas when synthetic muramyl dipeptides combined with trehalose dimycolate in oil-in-water emulsions were injected directly into the tumors. These compounds are promising candidates to replace viable bacillus Calmette-Guérin in cancer immunotherapy in humans and animals.

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Die Umsetzung des Bromids (I) mit dem [aus den Komponenten (II) und (III) gebildeten] Enamin (V) liefert das Pyrrol (IVa) (Hantzsche Pyrrolsynthese) ; Cyclisierung des aus (IVa) über das Mesylat (IVb) erhältlichen Iodids (IVc) gibt das Pyrrolopyrrol (VIa), das über die Stufen (VIb), (VIc) in den Ester (VIIa) bzw. dessen Verseifungsprodukt (VIIb) übergeführt wird.