Enamine-ketones solubility

High solubilities in organic solvents of these compounds together with the low transition temperatures suggest possible processability for the poly(enamine-ketones) as high strength materials. 

In contrast to the poly(enamine-ketones) prepared by Imai e al. the methyl substituted poly(enamine ketones), J 2, prepared from the condensation of diamines and bis-acetylacetylarenes, were found to be hydrolytically stable and thermally stable from 257 to 340 C, When a linear and rigid aromatic bis(1,3-diketone) was condensed with alkaline dieamines with ten or more carbons or with rigid aromatic diamines, thermotropic liquid crystalline materials were obtained. The monomers and polymers have much higher solubilities and lower transition temperatures as compared with liquid crystals containing only aromatic hydrocarbon rings of similar structures. 

Protocol 6 involves heating Mannich compound 10 in DMSO, apparently causing elimination of dimethylamine and formation of enone 20 as a reactive intermediate. The corresponding enone has been synthesized in the 9-butyl series,6,22 but comparable yields are obtained in pyridine cyclization reactions involving either the preformed enone or the Mannich HQ salt.7 Prior to addition of 10, ketone 9 is heated with ammonium chloride in DMSO to promote the formation of imine 21. Isomerization of this imine to the enamine tautomer 22, Michael addition of this nucleophile to enone 20, and elimination of water account for the formation of product 11. Like many polycyclic terpyridyl analogues, this product is sparingly soluble in DMSO and is readily isolated by filtration of the reaction mixture. 

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