Author Topic: Safrole via Friedel Craft?  (Read 1006 times)

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amine

  • Guest
Safrole via Friedel Craft?
« on: August 15, 2004, 11:56:00 PM »
i'm curious to the possibility of synthesizing safrole from 1,3-benzodioxole and allyl bromide using the zinc method:

Post 408642

(Kinetic: "Zinc promoted Friedel-Crafts acylation", Novel Discourse)
.

I knows alkylations can me done this way but I am unsure whether the double bond on the allyl bromide would in some way hinder the reaction.

Thanks.

yei

  • Guest
Hinder, no, but...
« Reply #1 on: August 17, 2004, 06:22:00 AM »
First, you will not get only the isomer you desire, because AFAIK, the allyl chloride or bromide will also alkylate ortho to the methylenedioxy structure.

Second, using normal friedel-crafts methods will generate HBr acid, which will tend to add across the allyl double bond, and possible cause multiple alkylations and polymerization. There are ways around this:

Post 468541 (missing)

(ning: "high-yielding OTC allylation of aromatics, anyone?", Chemistry Discourse)
scrubs up HX with supported K2CO3

Post 515205

(psyloxy: "TsOH - best Friedel-Crafts catalyst ever ?!", Novel Discourse)
uses tosic acid to catalyze the magical alkylation

anyhow, it's not so easy as it seems.