2-(2-Methyl-allyloxy)-pent-4-enoic acid ethyl ester → 5-methyl-3,6-dihydro-2H-pyran-2-carboxylic acid ethyl ester
Reaction equation
[CH2:1]([O:3][C:4](=[O:14])[CH:5]([O:9][CH2:10][C:11]([CH3:13])=[CH2:12])[CH2:6]C=C)[CH3:2]>C(Cl)Cl>[CH2:1]([O:3][C:4]([CH:5]1[CH2:6][CH:13]=[C:11]([CH3:12])[CH2:10][O:9]1)=[O:14])[CH3:2]Participants
3
Reactant 1
Product 1
Reagents, catalysts & solvents 1
Procedure
To a refluxing stirred solution of 2-(2-methyl-allyloxy)-pent-4-enoic acid ethyl ester (396 mg, 2.0 mmol) in CH2Cl2 (100 mL, 0.02 M solution) was added drop wise a solution of the tricyclohexylphosphine (1,3-Bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene)(benzylidine)ruthenium (IV) dichloride (85 mg, 0.1 mmol) in CH2Cl2 (3.0 mL). After 50 min, the reaction mixture was cooled to room temperature, concentrated and purified on silica gel bond elute using EtOAc/hexane (1:20) as an eluent furnished 5-methyl-3,6-dihydro-2H-pyran-2-carboxylic acid ethyl ester (320 mg, 92% yield) as a brown oil. NMR 1H (CDCl3, 400 MHz): 5.51 (br s, 1H), 4.28-4.08 (m, 4H), 2.32 (brs, 3H), 1.29 (t, J=7.2, 3H).