Pyranocoumarins

Coumarin (/ˈkuːmərɪn/) or 2H-chromen-2-one is an aromatic organic chemical compound with formula C9H6O2. Its molecule can be described as a benzene molecule, with two adjacent hydrogen atoms replaced by a lactone-like chain –(CH)=(CH)–(C=O)–O–, forming a second six-membered heterocycle that shares two carbons with the benzene ring. It can be placed in the benzopyrone chemical class, and as a lactone. Coumarin (/ˈkuːmərɪn/) or 2H-chromen-2-one is an aromatic organic chemical compound with formula C9H6O2. Its molecule can be described as a benzene molecule, with two adjacent hydrogen atoms replaced by a lactone-like chain –(CH)=(CH)–(C=O)–O–, forming a second six-membered heterocycle that shares two carbons with the benzene ring. It can be placed in the benzopyrone chemical class, and as a lactone. Coumarin is a colorless crystalline solid with a sweet odor resembling the scent of vanilla and a bitter taste. It is found in many plants, where it may serve as a chemical defense against predators. By inhibiting synthesis of vitamin K, it is used as the prescription drug, warfarin – an anticoagulant – to inhibit formation of blood clots, deep vein thrombosis, and pulmonary embolism. Coumarin is derived from coumarou, the French word for the tonka bean. The word tonka for the tonka bean is taken from the Galibi (Carib) tongue spoken by natives of French Guiana (one source for the plant); it also appears in Old Tupi, another language of the same region, as the name of the tree. The old genus name, Coumarouna, was formed from another Tupi name for tree, kumarú. Coumarin was first isolated from tonka beans in 1820 by A. Vogel of Munich, who initially mistook it for benzoic acid. Also in 1820, Nicholas Jean Baptiste Gaston Guibourt (1790–1867) of France independently isolated coumarin, but he realized that it was not benzoic acid. In a subsequent essay he presented to the pharmacy section of the Académie Royale de Médecine, Guibourt named the new substance coumarine. In 1835, the French pharmacist A. Guillemette proved that Vogel and Guibourt had isolated the same substance. Coumarin was first synthesized in 1868 by the English chemist William Henry Perkin. Coumarin has been an integral part of the fougère genre of perfume since it was first used in Houbigant's Fougère Royale in 1882. Coumarin can be prepared by a number of name reactions with the Perkin reaction between salicylaldehyde and acetic anhydride being a popular example. The Pechmann condensation provides another route to coumarin and its derivatives; as does the Kostanecki acylation which can also be used to produce chromones. Coumarin is found naturally in many plants, notably in high concentration in the tonka bean (Dipteryx odorata). It also occurs in vanilla grass (Anthoxanthum odoratum), sweet woodruff (Galium odoratum), sweet grass (Hierochloe odorata) and sweet-clover (genus Melilotus), which are named for the sweet (i.e., pleasant) smell of the compound.