Tetrahedron

Synthetic studies related to diketopyrrolopyrrole (DPP) pigments. Part 2: The use of esters in place of nitriles in standard DPP syntheses: Claisen-type acylations and …

…, DM Smith, NJ Westwood, P Lightfoot, AMZ Slawin

Index: Morton, Colin J.H.; Riggs, Richard L.; Smith, David M.; Westwood, Nicholas J.; Lightfoot, Philip; Slawin, Alexandra M.Z. Tetrahedron, 2005 , vol. 61, # 3 p. 727 - 738

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Citation Number: 31

Abstract

Ethyl 2-aryl-4, 5-dihydro-5-oxopyrrole-3-carboxylates react with esters or acyl halides in the presence of a strong base to give 4-acyl derivatives, which exist predominantly as either E- or Z-enols. These are cyclised, either in solution at temperatures> 200° C or by microwave irradiation, to 3, 6-disubstituted 1H-furo [3, 4-c] pyrrolediones which, after N-protection, are convertible by reaction with primary amines into novel N, N′-disubstituted DPP ...