Coumarin derivatives

Coumarin derivatives are derivatives of coumarin and are considered phenylpropanoids.^[1] Among the most important derivatives are the 4-hydroxycoumarins, which exhibit anticoagulant properties, a characteristic not present for coumarin itself.

Some naturally occurring coumarin derivatives include umbelliferone (7-hydroxycoumarin), aesculetin (6,7-dihydroxycoumarin), herniarin (7-methoxycoumarin), psoralen and imperatorin.

4-Phenylcoumarin is the backbone of the neoflavones, a type of neoflavonoids.

Coumarin-pyrazole hybrids have been synthesized from hydrazones, carbazones and thiocarbazones via Vilsmeier Haack formylation reaction. Whereas, coumarin-pyridine hybrids have been prepared from the Knoevenagel condensation of pyridylacetontriles with substituted salicylaldehydes.^[2]

Compounds derived from coumarin are also called coumarins or coumarinoids; this family includes:

• brodifacoum^[3][4]
• bromadiolone^[5]
• difenacoum^[6]
• auraptene
• ensaculin
• phenprocoumon (Marcoumar)
• PSB-SB-487
• PSB-SB-1202
• scopoletin can be isolated from the bark of Shorea pinanga^[7]
• warfarin (Coumadin)

Coumarin is transformed into the natural anticoagulant dicoumarol by a number of species of fungi.^[8] This occurs as the result of the production of 4-hydroxycoumarin, then further (in the presence of naturally occurring formaldehyde) into the actual anticoagulant dicoumarol, a fermentation product and mycotoxin. Dicoumarol was responsible for the bleeding disease known historically as "sweet clover disease" in cattle eating moldy sweet clover silage.^[8][9] In basic research, preliminary evidence exists for coumarin having various biological activities, including anti-inflammatory, anti-tumor, antibacterial, and antifungal properties, among others.^[8]

Warfarin – a coumarin – with brand name, Coumadin, is a prescription drug used as an anticoagulant to inhibit formation of blood clots, and so is a therapy for deep vein thrombosis and pulmonary embolism.^[10][11][12] It may be used to prevent recurrent blood clot formation from atrial fibrillation, thrombotic stroke, and transient ischemic attacks.^[12]

Coumarins have shown some evidence of biological activity and have limited approval for few medical uses as pharmaceuticals, such as in the treatment of lymphedema.^[10][13] Both coumarin and 1,3-indandione derivatives produce a uricosuric effect, presumably by interfering with the renal tubular reabsorption of urate.^[14]

Arising from tunable intramolecular charge transfer (ICT) properties within the molecule, coumarins have found purpose as dyes and stains, particularly those featuring electron-donating substituents at the 7-position, which can be used to enhance this behavior. Coumarin dyes are extensively used as gain media in blue-green tunable organic dye lasers.^[15][16][17] Among the various coumarin laser dyes are coumarins 480, 490, 504, 521, 504T, and 521T.^[17] Coumarin tetramethyl laser dyes offer wide tunability and high laser gain,^[18][19] and they are also used as active medium in coherent OLED emitters.^{[20][15][16][17]} and as a sensitizer in older photovoltaic technologies.^[21]

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