Ketones from Propenylbenzenes via the di-bromides

[Osmium]

Are you sure about the asarone epoxide rearrangement being in Houben-Weyl??? I know I saw the isosafrole rearrangement a few years back, but asarone? Very strange, I doubt I would have overlooked that.

> The anethol run as described by Osmium ...

Huh? What did I describe? Wasn't me for sure.

[uemura]

Osmium,
you described it for isosafrole in 'MDP2P from Isosafrole via Epoxide Intermediate' (see

https://www.thevespiary.org/rhodium/Rhodium/chemistry/safrolepoxide.html

) . It worked for anethole as specified.
Where to check in the Houben-Weyl? Uemura has identified the volume which contains 'Preparation and Reactions of Epoxides' (appr. 100pages). Should it be in here or under other volumes dealing with ketones, or oelefins or.... Carpe Diem

[otto]

hi uemura and osmium,

i am not quite shure, i think it was in one of the ketone-volumes. there was a table given w/ various epoxides and refs. it was also stated that there will be a certain amount of the 1-ketone depending on the epoxide.
unfortunately right now otto has no access to the Houben-Weyl.
the 2,3-epoxide will also rearrange to give the 2-ketone. but i doubt that a similar preparation via the dibromide would work. the first bromine in the ISO-dibromo-compounds is benzylic, therefore easily exchanged, in the 2,3-dibromos its not.
otto is questioning, wether a different pathway would be possible. having the halohydrine, one could try to exchange the halogene with ammonia giving a propanolamine. this could be converted into the corresponding amphetamine by oxidation to the aminoketone and its subsequent (Clemmensen-)reduction.

otto

[Rhodium]

I doubt the aminoketone can be reduced in good yields with the clemmensen. The acidic conditions seem to invite the compound to dimerize.

[twodogs]

Uemura...The epoxide to ketone rearrangement by heating was discussed in a thread in Chemistry Discource called "Li catalysed pinacol rearrangement possible?" The reference you are looking for regarding this is Methoden der Organischen Chemie Pg 934 Volume 7,2(a) Ketones. This has a table with a number of epoxide to ketone reactions by simply heating. Reference is also made to  P Hoering - Ber Vol 38 Pg 3477 (1905). He states that both Isosafrole and the Anisyl epoxides produce the ketone when distilled.  10 grms of the isosafrole epoxide heated to 220C -280C distills over giving 8 grms of the ketone. Reference is also made to Compte Rendus 141, 662 (1905) and Annale de Chemie ( 10 192 (1907)
I also again state that this rearrangement occurs when glycols are heated. Have a look at that thread.

[uemura]

twodogs,
thanks for posting the Houben-Weyl reference. Uemura will check it out, same for the "Li catalysed pinacol rearrangement possible?" thread. The Hoering - Ber Vol 38 Pg 3477 (1905) paper is the one Uemura first found and used for this thread. Carpe Diem

[halfapint]

The asarone ketone from the epoxide simply by heating, no acid present? Oxone!
turning science fact into <<science fiction>>

[uemura]

twodogs... The epoxide to ketone rearrangement by heating was discussed in a thread in Chemistry Discource called "Li catalysed pinacol rearrangement possible?"
Do you have the number for that post? Uemura's search hasn't been successful. Thanks Carpe Diem

[twodogs]

Uemura... The first post in that thread is

Post 218193 (missing)

(Ritter: "LiI catalyzed pinacol rearrangement possible?", Chemistry Discourse)

[uemura]

twodogs! Uemura apologizes his claim to have first submitted the thermal rearrangement rxn from epoxides to ketones. He just didn't catch the reference you have given in your post. Mea maxima culpa  

[sunlight]

Just heating the epoxyde or even de diol we get the ketone... Wow !!!
The literature says that KMnO4 in cold and neutral or basic conditions oxydize alkene to diols, but I've never seen it for safrol/isosafrol/asarone... Has it been tested ?
What about hidrohalogenation with sodium hypochlorite w/o strong acid ?
And other ways to produce the epoxyde ?

[Rhodium]

Yes, Ritter has tested the procedure (used the one from The Complete Book of Ecstacy) but he thought the solvent volume was impractical (and it cannot be made more concentrated, or the KMnO4 will cleave the side chain).

I don't understand why noone has tested the hypochlorite or hypobromite route to the halohydrin, and then made the epoxide from that with a base. It is OTC, and very simple.

[sunlight]

Mmmm, another time the volumes, shit.
Do you have any example of a halohydroxylation ?
There's another rxn that may be interesting, Milas hydroxylation, H2O2 and hv or Cr oxyde/Os/V in catalytic amount. Reference are from JACS 1936...1940, has anyone acces to them ?
Wich is the reason to start all these rxns with iso and not with safrol directly ?

[otto]

hi sunlight,

in answer to your last question: as long as you go via the epoxide there is no reason to start with the iso instead of the safrole since the 2,3-epoxide (formed from safrole) will give the desired 2-ketone, too. (ref: houben- weyl, vol. 7,2,a, p. 932; comptes rendues 184,1335,(1927))

otto

[sunlight]

Thanks otto.
I have still darks points about the subject, please see if you can clarify them.
I asume that peracid rxn with safrol gives "a complicated mixture of products".
Isosafrol diol, monoformyl glycol or epoxide rearranges to 2 ketone with H2SO4 or just heating (at least the epoxide), but what could happen with the diol or epoxide of safrol with the same procedure ? Would it be necessary to use LiI to rearrange the epoxide ?
Thanks.

[terbium]

Do you have any example of a halohydroxylation ?
Check out the Curriculum Vitae of this fellow, D.R. Dalton. Besides writing a book on alkaloid chemistry he has also written a number of papers on the preparation of bromohydrins/halohydrins using dimethyl sulfoxide as a solvent.

http://astro.ocis.temple.edu/~dalton/drdcv.htm

[otto]

hi sunlight,

using safrol in the performic will propably give the 2,3-diol, the formyl ester is easily hydrolised as soon as it gets in contact to aqueous medium. i doubt that you would get the epoxide.
concerning the rearrangement: i dont know wether the 2,3-diol will give the 2-ketone. what if not? i would rather expect the (3-arylpropionyl-) aldehyde to be formed.
the epoxide will certainly give the 2-ketone as literature says.

otto

[sunlight]

Very impressive !!!

[Vibrating_Lights]

Are yall saying that safrole con be put into a peracid oxidation and the resulting epoxide rearranged to MDP2P.  how would one go about seperating the epoxide from the other products.

[Rhodium]

Safrole can be made into its 2,3-epoxide in a number of ways (oxone or Acetonitrile/H2O2), but not a peracid reaction, which forms the glycol. If you make the 2,3-epoxide, it can be rearranged to MDP2P using LiI, LiBr and MgBr2 (among other reagents), but if it is subjected to the regular isosafrole treatment, there is a big risk that undesired aldehydes are formed instead.