Formaldehyde → (S)-2-[(4aR,5S,8aS)-5-(tert-butyldimethyl-silanyloxy)-8a-methyl-3,4,4a,5,6,7,8,8a-octahydronaphthalen-1-yl]-propan-1-ol

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of 3.11 g (10.1 mMol) of (1S,4aS,8aR)-tert-Butyl-(5-ethylidene-4a-methyl-decahydro-naphtalen-1-yloxy)-dimethylsilane in 125 ml of toluene are added 0.33 g (11.1 mMol) of finely powdered paraformaldehyde. The reaction mixture is cooled to 0° C. and 12.56 ml of a one molar solution of dimethylaluminumchloride in hexane are added and kept for one hour at this temperature. The reaction mixture is stirred at room temperature overnight, diluted with diethylether, washed with 1N HCl and with water, then dried over sodium sulfate and evaporated in vacuo. The residue is chromatographed over a medium pressure 250 g silicagel column with hexane/ethylacetate 9/1 to yield 2.31 g (67.5%) of pure (S)-2-[(4aR,5S,8aS)-5-(tert-butyl-dimethyl-silanyloxy)-8a-methyl-3,4,4a,5,6,7,8,8a-octahydro-naphtalen-1-yl]-propan-1-ol as an oil. By running the reaction with BF3.Et2O in CH2Cl2 small amounts of the (R)-epimer, the starting material of Examples 31-33 can be isolated.

Provenance & Evidence