3H-2-Benzopyran-3-ones

Complete aromaticity in coumarin (19), isocoumarin (28) and 3H- 2- benzopyran-3-one (206) can only be realized if the O—CO function contributes two electrons to form a 1077-electron system, which would necessarily possess a betaine structure. 

H)-Furanone, 3,5,5-trimethyl-2(5H)-Furanone, 4,5,5-trimethyl-7H-Furo[3,2-g][1]benzopyran-7-one, 4-methoxy-Furo[3,2-b]furan-2(3H)-one, tetrahydro-3a-methyl-... 

Dihydro-5-pentyl-2(3h)-furanone 9,10-Dihydrophenanthrene 2,3-Dihydro-2-phenyl-4W-1-benzopyran-4-one 4,5-Dihydro-2-(phenylmethyl)-1//-imidazole, monohydrochloride... 

Trihydroxy-3,3-dime thy 1-5, ll-bis 3-methyl-2-butenyf)-3H,7 l-benzofuro[2,3-b]pyrano[2,3-b][l]benzopyran-7-one,... 

Lewis acids were shown to have a remarkable influence in the facial selectivity in the cycloadditions of sugar-derived dihydropyranones. Using BF3 OEt2 as a Lewis acid, the reaction between 2,3-dimethylbutadiene and (2S)-2-benzyloxy-2H-pyran-3-(6H)-one (17), affords a 98 2 ratio of (3S,4aR,8aS) versus (3S,4aR,8aR)-3-benzyloxy-6,7-dimethyl-4a,5,8,8a-tetrahydro-lH-2-benzopyran-4(3H)-one. The same reaction under the influence of SnCU gives a complete reversal in facial selectivity with a 24 76 ratio of products (Equation 13) [19]. 

CAS 21280-29-5 EINECS/ELINCS 244-310-6 Synonyms Decahydro-4-a-hydroxy-2,8,8-trimethyl-2-naphthoic acid, y-lactone 3,8a-Ethano-8aH-1-benzopyran-2(3H)-one, hexahydro-3,5,6-trimethyl- Hexahydro-3,5,5-trimethyl-3,8a-ethano-8aH-1-benzopyran-2(3H)-one Lactoscatone Classification Lactone Empirical C14H22O2 Properties M.w. 222.36 Toxicology LD50 (oral, rat) 1600 mg/kg, (skin, rabbit) > 5 g/kg mod. toxic by ing. low toxicity by skin contact TSCA listed Hazardous Decomp. Prods. Heated to decomp.,... 

Hexahydro-3,5,5-trimethyl-3,8a-ethano-8aH-1-benzopyran-2(3H)-one. See Decahydro-2,8,8-trimethylnaphthalene-2,4a-carbolactone Hexahydro-1,3,5-trinitroso-s-triazine. See Hexahydrotriazine... 

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