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Joined 2026-09-21 Message
Incoming links: Methylamine
Disconnect the amide into 2-propylhexanoic acid and N-methyl-2-(4-hexylphenyl)ethylamine. This keeps the nitrogen substituents distinct: one is Me and the other is the two-carbon aryl side chain. The acid's alpha carbon must bear both n-butyl and n-propyl groups.
For the acid fragment, esterify the supplied hexanoic acid, form its ester enolate with LDA, and alkylate with 1-iodopropane:hydrolysis gives 2-propylhexanoic acid; conversion with gives the acyl chloride for the final coupling. Limit the alkylating reagent and isolate the monoalkylated ester to avoid overalkylation.
For the aryl fragment, use another portion of hexanoic acid to make hexanoyl chloride. A Friedel-Crafts acylation of bromobenzene with this reagent and gives ortho and para products; isolate the para bromoaryl ketone. A Wolff-Kishner reduction converts into without deliberately hydrogenolyzing the aryl bromide. Acylation followed by carbonyl reduction installs an unrearranged n-hexyl group; direct Friedel–Crafts alkylation is a less reliable way to do that.
Convert the retained aryl bromide into its grignard reagent, open ethylene oxide, and work up to obtain . Oxidize the primary alcohol to under conditions that stop at the aldehyde, then perform reductive amination with methylamine and sodium triacetoxyborohydride. Excess methylamine helps favour the desired secondary amine over further alkylation. Finally acylate that secondary amine with the isolated acyl chloride, using a separate base to capture HCl.
The final amide has an N-methyl group, the para n-hexyl phenethyl group, and the required n-butyl/n-propyl acyl branching. The carbon check is in the acyl fragment plus in the amine fragment, giving overall. No absolute stereochemistry is specified at the acid alpha carbon.