O-Cresol → (E)-3-o-tolyloxy-but-2-enoic acid ethyl ester

Reaction equation

[CH3:1][C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][C:3]=1[OH:8].[CH2:9]([O:11][C:12](=[O:16])[C:13]#[C:14][CH3:15])[CH3:10].N12CCCN=C1CCCCC2>O1CCCC1>[CH2:9]([O:11][C:12](=[O:16])/[CH:13]=[C:14](/[O:8][C:3]1[CH:4]=[CH:5][CH:6]=[CH:7][C:2]=1[CH3:1])\[CH3:15])[CH3:10]

Participants

Procedure

To a stirred mixture of 2-methyl-phenol (4.90 g, 0.045 mol) and ethyl-2-butynoate (10.1 g, 0.09 mol) in tetrahydrofuran (15 mL) was added 1,8-diazabicyclo[5.4.0]undec-7-ene (6.80 g, 0.045 mol) slowly. After addition was complete the mixture was stirred at reflux for 6 h. Upon completion of the reaction the tetrahydrofuran was removed in vacuo and the residue was diluted in diethyl ether and washed first with 1N aqueous hydrochloric acid, then 10% aqueous sodium hydroxide solution, a saturated sodium chloride solution and dried over magnesium sulfate. The crude product, (E)-3-o-tolyloxy-but-2-enoic acid ethyl ester, was obtained as a brown oil (6.45 g, 65%) and used without further purification.