pHarmacist (pHantasticant)
07-11-03 02:43
No 446390
      ortho-isocyanotoluenes in indole synthesis  Bookmark   

First, I want to appologise for not having any experimental detailes on hand. I'll come back with detailes regarding cyclisation of the benzylic anions derived from ortho-isocyanotoluenes into indoles.

A simplest example:

ortho-isocyanotoluene --2xLDA/diglyme/(-78C to rT),H2O--> Indol (100% yield)

However, here is one of general experimental procedures for the transformation to a isocyanide function, product is phenylisocyanide:

A solution of 11.5 grams of cyanogen bromide in 15 ml. of methylene chloride was added at 0 < C, with stirring, to a solution of 13.7 grams of thioformanilide in 30 grams of triethylamine and 30 ml. of methylene chloride.

After 30 minutes, the reaction mixture was poured into water, the organic phase was separated, dried with anhydrous potassium carbonate, filtered and fractionally distilled. There were obtained 6.8 grams of phenyl isocyanide (66 of the theoretical) boiling point 68 to 700/12 mm.

I'll be back (in this thread) with the above-mentioned cyclisations that yield indoles in excellent yields, you guys are welcome to post if you have anything on this route...

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