Synthesis of 1-[3-(dimethylamino)prop-1-yn-1-yl]cycloheptanol

Preparation of 1-[3-(dimethylamino)prop-1-yn-1-yl]cycloheptanol

To a solution of lithium amide (prepared from 2.2 g of lithium) in 400 ml of liquid ammonia are added 30 g of 2-bromo-3-diethylaminopropl-ene and the mixture stirred for 4 hours. A solution of 11.2 g of cycloheptanone in 15 ml of dry ether are then added dropwise during 30 minutes and the stirring continued for a further 4 hours. After introduction of 10 g of powdered ammonium chloride the ammonia is allowed to evaporate off and the residue treated with 2N sulfuric acid and ether. The aqueous layer is then further extracted with ether; drying, evaporation and distillation of the combined ethereal extracts furnishes unchanged 4.2 g of cycloheptanone. Basification of the aqueous layer and isolation by means of ether gives the required alcohol 9.9 g or 72% of 1-[3-(dimethylamino)prop-1-yn-1-yl]cycloheptanol as a viscous oil b.p. 102°/0.3 mm, nD=1.4985.

Acetylenic compounds in organic synthesis, by R. R. Alexander, 197-198, 1955

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