Phenyl 3-methylbut-2-enoate → 2H-1-Benzopyran-2-one, 3,4-dihydro-4,4-dimethyl-

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Reaction Steps

To a stirred, ice-cooled suspension of 10.4 g (78 mmol) of aluminum chloride in 160 ml of methylene chloride was added slowly under argon a solution of 7 g (39.8 mmol) of phenyl 3,3-dimethylacrylate (Compound 37) in 40 ml of methylene chloride. The cooling bath was removed and the mixture stirred for a further 42 h. The mixture was poured into a mixture of ice and brine and the organic layer separated. The aqueous layer was extracted with methylene chloride and the organic extracts were combined and washed with saturated NaCl solution and then dried (MgSO4). The solvent was removed in vacuo and the residue purified by flash chromatography (silica; 10% ether in hexane) to give the title compound as a colorless oil. PMR (CDCl3 : & 1.30 (6H, s), 2.56 (2H, s), 7.06 (1H, dd, J~8.0 Hz 1.4 Hz) 7.16 (1H, td, J~8.0 Hz, 1.4 Hz), 7.26 (1H, td, J~8.0 Hz, 1.7 Hz), 7.33 (1H, dd, J~8.0 Hz, 1.7 Hz). MS exact mass, m/e 176.0852 (calcd. for C11H12O2, 176.0837.

Provenance & Evidence