02-14-03 13:19
No 407891
This one is a nifty synthesis. 4-butynol is deprotonated in both ends, then silylated with chlorotrimethylsilane (or bulkier silanes for better yield), then cyclized through palladium catalysis to form tryptophol, silylated in the 2-position and on the oxygen function. The silyl groups are easily removed by reflux in methanolic HCl. Yield 60-80% of tryptophol depending on choice of silyl groups.
The next step is excellent and should be the method of choice for making tryptamines from tryptophols. Treatment with mesyl chloride followed by 40% aqueous dimethylamine gives DMT in 79% yield!
Reference: Tet Lett 35(38), 3981-3984 (1994) (../rhodium/pdf /dmt.butynol.
(Hive Bee)
02-14-03 15:35
No 407942
Beautiful reaction Rhodi, nice!
It's a shame that butynol is expensive tough...
(Chief Bee)
02-14-03 17:14
No 407966
Yup, fortunately there are many other roads to tryptophol, to which the latter part of the above synthesis can be applied. Instead of dimethylamine, just any dialkylamine should work.