Coumarin 4,4 -methylenebis-4-hydroxy-,

Coum rinic Acid Compounds. These synthetic phyUoquinone derivatives and congeners have been employed as anticoagulants since the isolation of 3,3 -methylenebis(4-hydroxy-2H-l-benzopyran-2-one) [66-76-2] (bis-4-hydroxycoumarin or dicoumarol) (1) from spoiled sweet clover in 1939. The ingestion of the latter was responsible for widespread and extensive death of bovine animals at that time. The parent compound for the synthesis of many congeners is 4-hydrocoumarin, which is synthesized from methyl salicylate by acetylation and internal cyclization. The basic stmctures of these compounds are shown in Figure 2, and their properties Hsted in Table 6 (see Coumarin). 

Dicoumarol — see Coumarin, 3,3 -methylenebis(4-hydroxy-Dictamnine biosynthesis, 4, 992 occurrence, 4, 989 pharmacology, 4, 992 synthesis, 4, 990 Dicyanocobyrinic acid heptamethyl ester, 4, 422 Dicycloalkaselenophenes synthesis, 4, 968 Dicyclohexa-1,4-diselenins thermolysis, 4, 968 Dieckmann condensation chroman-3-one synthesis by, 3, 854 isochroman-4-one synthesis by, 3, 859 oxoindolizidine synthesis by, 4, 471... 

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