Chromone special

Coumarins (76) and chromones (71) with other benzo derivatives number some important commercial compounds among their ranks. Coumarin itself (76) is the new-mown hay smell and the rat poison Warfarin (72) is a substituted coumarin. No special methods are needed for these easily made compounds as syntheses of Warfarin should demonstrate. 

Chromonic liquid crystals are a special class of lyotropic liquid crystals. Flat aromatic systems with polar substituents form columnar aggregates by n-n interactions in solution. The mesophases of concentrated DNA solutions or of copper-tetracarboxyphthalocyanine are examples for this. Special types of chiral mesophases have been observed [29]. 

Fluoroalkyl-substituted enones represent another important class of CCC bis-eletrophiles widely used for the preparation of pyrimidines with fluorinated alkyl at C-4. Their chemistry has been reviewed recently [435, 436], therefore, preparation of these bis-electrophiles is not discussed herein. Several subtypes of p-enones are amendable for the synthesis of chain-fluorinated pyrimidines. The most common group include compounds with a leaving group at p position (700-702 and 706). (Fig. 24). A special case of these bis-electrophiles is chromone derivatives and their hetero-analogues (704, 705). Other p-enones 703 i.e. non-functionalized) and 712 (P-sulfonyl, hydrates) are also used. 

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