nysted and tebbe's reagents are accesible means of methylenating proiophenone ala wittig.

attached is a patent detailing this a-ethylstryrene can be had from proiophenone in this manner.
 it appears the by-products (spectators0 are ZnO and mixed Zn salts like Zn2OBr2)
hmmm that's a prettty clean reaction/

the schmidle papers on the prins reactiion

SCHMIDLE & MANSFIELD, J. Amer. chem. Soc . 1955, 77, 5698.

026
Idem., ibid ., 1957, 77, 5754.


SCHMIDLE & MANSFIELD, U.S. 2, 765, 315

Recently, a new one-stage synthesis of the parent alcohol of the reversed ester of pethidine has been reported ([25] ). The method involves the amino-methylation of ?-methylstyrene by means of a methylamine hydrochloride-formalin mixture and gives the 4-piperidinol (XX) in 30% yield together with a substituted oxazine (XXI) as the major product. A modification of the method, employing N, N', N" -trimethyltrimethylenetriamine gives the reversed ester itself in 30% yield ([26] ); use of higher ?-substituted styrenes leads to prodine and its analogues ([67] ).

i've pored over the mechanism, I've  had a friend try this synth, nobody got parkinsons, i'm sure it won't happen.
i could detail the mechanis but tht would take all day.
 in the end you have an acyl ion,
(RCO2-) and a stabile tertiary carbocation where the rings meet up so it just adds to this and bam! this is only under anhydrous let me say again anhydrous conditions.
the acids are'nt strong enough to hydrolyse that ester and efecct E1 elimination of the piperinol to the tetrahydrpyridine ring it just won't happen.
mptp:
TLC rf=.42 on merck silica using a 1/3 methonol chloriform gradient it was visulized my means of iodoplatinate salts and u.v.
any questions??

re: Interesting, very interesting.  However, Wiki says "MPTP was first synthesized as an analgesic in 1947 by Ziering et al. It can be formed by mixing formaldehyde, methylamine and alpha-methylstyrene."  Any thoughts on this?


yeah look at the way it was formed it was formed from either the oxazine or the piperidinol first formed by mixing those aforementioned chemicals followed by treatment with hot concetrated strong acids so the actual cylization does not i repeat does not make mptp.
lower concetratrations of acid caused different reactions and these are the strong acids like H2SO4.
so this system is safe to handle.
this is no half baked assumption either, you have to read the patents, and journals; not wiki, to find this out.