7H-Benzocyclohepten-7-one synthesis
- Product Name:7H-Benzocyclohepten-7-one
- CAS Number:4443-91-8
- Molecular formula:C11H8O
- Molecular Weight:156.18
![8,9-Dihydro-5H-benzo[7]annulen-7(6H)-one](/CAS/GIF/37949-03-4.gif)
Yield:69456-01-5 80% ，4443-91-8 10%
Reaction Conditions:
Stage #1: 5,6,8,9-tetrahydrobenzo[7]annulen-7-onewith N-Bromosuccinimide;trimethylsilyl trifluoromethanesulfonate in acetonitrile at 20; for 4.5 h;
Stage #2: with 1,8-diazabicyclo[5.4.0]undec-7-ene in acetonitrile at 20; for 0.5 h;
Steps:
7.5.1. 6-Bromo-5,6,8,9-tetrahydrobenzocyclohepten-7-one (24) and 5,6-dihydrobenzocyclohepten-7-one (25)
3. Directly from ketone 9 and bromoketone 24: To a solution of 9 (0.5 g, 3.12 mmol) in MeCN (12 mL) were successively added SiMe3OTf (0.045 mL, 0.25 mmol, 0.08 equiv) and NBS (0.61 g, 3.5 mmol, 1.1 equiv). The solution was stirred at rt for 4.5 h (TLC monitoring. Treatment of the solution allowed isolating the rather unstable 24). DBU (1.03 mL, 7.0 mmol, 2.2 equiv) was added dropwise to the solution of crude 24 and the solution was stirred for further 30 minutes, then diluted with Et2O or AcOEt (100 mL) and washed with brine (2 × 20 mL). The organic layer was dried over MgSO4 and evaporated. Purification by flash chromatography (AcOEt/cyclohexane 2:8) gave 25 (0.42 g, 80%) as a brownish oil, and by further elution, the benzocycloheptene-3-one (40-70 mg, ca 10%, resulting from the elimination of a 6,8-dibromo-compound).
References:
Albrecht, Sebastien;Al-Lakkis-Wehbe, Mira;Orsini, Alban;Defoin, Albert;Pale, Patrick;Salomon, Emmanuel;Tarnus, Celine;Weibel, Jean-Marc [Bioorganic and Medicinal Chemistry,2011,vol. 19,# 4,p. 1434 - 1449] Location in patent:experimental part
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