Pseudo-Stobbe condensation

A second new route to DPP Pigments was developed and published 1983 In this route, succinic ester is condensed in a pseudo-Stobbe condensation with an aromatic nitrile in the presence of strong base to afford the desired DPP in good yield (Stdieme 11—4). Mechanistically, the formation of a DPP unit from succinic esters is believed to proceed along the pathway shown in Scheme 11—4. TTie initially formed enaminoesters 5C/5D cyclize to the pyrrolinone esters 6B, which further react under basic conditions with another benzonitrile. Subsequent ring closure affords the DPP 2. 

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See also in sourсe #XX -- [ ]

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