(4R)-2-(N,N-diethylamino)methyl-4-(tert-butyldimethylsiloxy)cyclopent-2-en-1-one → (3R,4R)-2-methylene-3-[(3S)-3-(tert-butyldimethylsiloxy)-3-cyclohexylprop-1-ynyl]-4-(tert-butyldimethylsiloxy)cyclopentan-1-one

Participants

Reaction Steps

In toluene (80 ml) was dissolved (3S)-3-(tert-butyldimethylsiloxy)-3-cyclohexylprop-1-yne (6.58 g), and n-butyl lithium (3.0 M, hexane solution, 8.0 ml) was added at 0° C., followed by stirring at the same temperature for 30 minutes. To the solution was added diethylaluminum chloride (0.95 M, hexane solution, 29.0 ml) at 0° C., followed by stirring at room temperature for 30 minutes. To the solution was added (4R)-2-(N,N-diethylamino)methyl-4-(tert-butyldimethylsiloxy)cyclopent-2-en-1-one (0.25 M, toluene solution, 80.0 ml) at room temperature, followed by stirring for 15 minutes. The reaction solution, while stirring, was added to a mixture of hexane (190 ml), a saturated aqueous ammonium chloride solution (190 ml) and an aqueous hydrochloric acid solution (3 M, 56 ml), and the organic layer was separated and washed with a saturated aqueous sodium bicarbonate solution (50 ml). The resulting organic layer was dried over anhydrous magnesium sulfate, filtered and concentrated, and the resulting residue was purified by a silica gel column chromatography (developing solvent; hexane:ether=10:1) to give (3R,4R)-2-methylene-3-[(3S)-3-(tert-butyldimethylsiloxy)-3-cyclohexylprop-1-ynyl]-4-(tert-butyldimethylsiloxy)cyclopentan-1-one (7.92 g).

Provenance & Evidence