ChemicalBook CAS DataBase List 8,9-Dihydro-5H-benzo[7]annulen-7(6H)-one

8,9-Dihydro-5H-benzo[7]annulen-7(6H)-one synthesis

10synthesis methods

Product Name:8,9-Dihydro-5H-benzo[7]annulen-7(6H)-one
CAS Number:37949-03-4
Molecular formula:C11H12O
Molecular Weight:160.21

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8,9-Dihydro-5H-benzo[7]annulen-7(6H)-one

37949-03-4
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Yield:37949-03-4 84%

Reaction Conditions:

Stage #1: dimethyl 7-oxo-6,7,8,9-tetrahydro-5H-benzo[7]annulene-6,8-dicarboxylatewith sulfuric acid in water;acetonitrile;Inert atmosphere;
Stage #2: with sodium hydroxide in diethyl ether;water;acetonitrile;

Steps:

3

Preparation 3 5,6,8,9-tetrahydro-benzocyclohepten-7-one (compound having the formula II) The isomeric mixture of dimethyl 7-oxo-5,6,8,9-tetrahydrobenzocycloheptene-6,8-dicarboxylate (80 g) obtained according to preparation 2 is refluxed in a 3M aqueous sulphuric acid (300 mL) and acetonitrile (50 mL) solution overnight under argon. The mixture is diluted with diethyl ether, neutralized with a 2M aqueous sodium hydroxide solution (3*300 mL), dried on magnesium sulphate and evaporated to dryness. The residue is distilled off at 97-98° C. under 0.4-0.5 Torr to obtain colourless crystals (26.1 g, 84% from α,α'-dibromo-o-xylene). Melting point: 43-44° C. ¹H-NMR (CDCl₃): 7.23 (m, 4 Har); 2.91 (m, 2H-C(6), 2H-C(8)); 2.62 (m, 2H-C(5), 2H-C(9)).

References:

US2010/69504,2010,A1 Location in patent:Page/Page column 5