01-26-03 13:03
No 401569
      About methyldopa
(Rated as: good idea!)

Well, swink knows that methyldopa is a cheap-as-dirty precursor for phenylacetones as described in ../rhodium/chemistry /p2p.strecker.html, although he isn't an especialist, he understood that that methyldopa ethers are more "yieldy" than the methyldopa alone, probably due to its stability to oxidations.
So he said: Whynotjustmethylenedioxyit?
after a fast search at esp@cenet he found this from GB1447599:

 Example 1
A. Preparation of L-3-(3,4-diphenylmethylenedioxyphenyl)-2-methylalanine hydrochloride

A mixture of 19.3 g (0,0777 mole) of L-3-(3,4-dihydroxyphenyl)-2-methylalanine hydrochloride [L-a-methyldopa hydrochloride] and 37 g (0.156 mole) of dichlorodiphenylmetane is imersed with slow stirring in a preheated oil bath at 190 C. After reaction has started, as evidenced by vigorous gas evolution, the reaction mixture is stirred rapidly for six minutes at 190 C, removed from the hot oil bath and allowed to cool to 25-30 C. The crude product from 12 runs is combined, slurried with 3 l of diethyl ether, filtered, washed with an aditional 2 l of diethyl ether and dried at 30 C under 50 mm pressure. Recrystallization is accompplished by dissolving the product in ethano and adding ethyl acetate to precipitate the product. The procedure gives 255 g 66.4%)of L-3-(3,4-diphenylmethylenedioxyphenyl)-2-methylalanine hydrochloride, m.p. 267-268 C.

Well, he knows that the reactivity of dichlorodiphenylmetane is greater than that of DCM, but he knows that there are some bees experienced with this type of reaction, so he is asking for help, any thougths?

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