> Your haloethylamine route won't work unless you protect the nitrogen, since it will either react with the Lewis acid, or with the other end of the ethylamine chain once the halogen is pulled off.
Okay, thanks...
> The Lewis acid/nitrile interaction is a bit more interesting, and there is very little information here on a reaction which may occur;
Okay, so acetonitrile survives ZnCl2? That's something. However, diazomethane sounds a little dangerous to handle, I must say.
If one is already going to set up for handling poisonous gasses and everything, I guess one could attempt to make the phenylacetone by Friedel-Crafts with chloroacetone as in
https://www.thevespiary.org/rhodium/Rhodium/chemistry/phenylacetone.html
, although the reported yields for benzene are low.
> I'm assuming you're trying to alkylate a 2-substituted 1,4-dimethoxybenzene. If this is the case, I have a feeling Friedel-Crafts alkylation will be very hard to do without demethylating the methoxies, since the stronger Lewic acids and harsher conditions needed are more likely to do this.
Okay? Well, I think the methoxies are a bit activating and with the methyl also there I think it would be pretty active. In any case, even if a strong catalyst is required, merely adding a drop of bromine to some aluminum foil in a chloroform should be all that is necessary to form a little aluminum tribromide in solution, though obviously not with ketone products which require molar equivalents of the Lewis acid.
> It may be possible, but there is probably a reason Shulgin acylated his dimethoxybenzenes then reduces the ketone to the alkane via a Clemmensen reaction.
You mean instead of just F-C alkylating with alkyl halides? I don't know, didn't he start with 1,4-dimethoxybenzene, which would produce the para-dialkyl derivatives if F-C alkylated?
Actually, that might not be so bad an idea. Dialkylating 1,4-dimethoxybenzene using methyliodide + Lewis acid should produce 2,5-dimethoxy-4-methyltoluene, right?
Oxidation using persulfate like once mentioned by
Post 208719
(Osmium: "Re: The easiest synth of benzaldehyde from toluene", Chemistry Discourse) will probably yield 2,5-dimethoxy-4-methylbenzaldehyde in good yield, since the reaction with xylene is facile.
If 1,4-dimethoxybenzene could be dialkylated using methanol instead of methyl halides, this might not be such a bad route to the benzaldehyde. As a google-search reveals, the alkylation reaction is facile with tert-butanol, but that says nothing about the less branched alcohols of course.