Methanol → 2-(Methoxymethylidene)-3,4-dihydronaphthalen-1(2H)-one
Reaction equation
[CH:1]([CH:3]1[CH2:12][CH2:11][C:10]2[C:5](=[CH:6][CH:7]=[CH:8][CH:9]=2)[C:4]1=[O:13])=[O:2].S(=O)(=O)(O)O.[CH3:19]O>>[CH3:19][O:2][CH:1]=[C:3]1[CH2:12][CH2:11][C:10]2[C:5](=[CH:6][CH:7]=[CH:8][CH:9]=2)[C:4]1=[O:13]Participants
4
Procedure
The 2-formyl-1-tetralone derivative of formula (3) is converted to the corresponding 2-enol ether of formula (4) by reacting a compound of formula (3) with an alcohol, preferably methanol, in the presence of a catalytic amount of a strong acid, preferably concentrated sulfuric acid. The reaction is preferably carried out at a temperature of about the reflux temperature of the alcohol, for about 5 minutes to 2 hours, preferably about 15 minutes. The product of formula (4), a 2-methoxymethylene-1-tetralone derivative, is isolated by conventional means, preferably by precipitation and filtration, and is reacted in the next step without any further purification.