Tetrahydrofuran → 4-Hydroxy-4-(phenylethynyl)-5-[2-(2,5,5-trimethyl-1,3-dioxan-2-yl)ethyl]-2-cyclohexen-1-one

Participants

Reaction Conditions

Reaction Steps

4-Hydroxy-4-(phenylethynyl)-2,5-cyclohexadiene-1-one (1.26 g, 0.006 mole), the compound of Example 1a and 25 mL of dry THF were placed in a dry 100 mL, three-necked round-bottomed flask under nitrogen. The reaction was cooled to -78° C. and treated dropwise with n-butyllithium (4 mL of 1.48M). The reaction was allowed to warm slowly to about 0° C. During this time, a white slurry formed. The reaction was cooled to -78° C. and treated with 4.6 mL of DMPU and one equivalent of the Grignard reagent prepared in Example 1b. The reaction was allowed to warm slowly to RT over a period of 1 hr, then quenched with ammonium chloride solution and extracted into ether. The ether extracts were washed with saturated brine and dried over anhydrous sodium sulfate. The organic phase was filtered and concentrated in vacuo. The residue was dried under vacuum overnight. The crude product was chromatographed using a flash silica gel column eluting with 1:4 EtOAc/hexane to yield a first compound-bearing fraction containing 1.5 g (68%) of the title 1,2-1,4 adduct and a third compound-bearing fraction containing 0.31 g (14%) of 1-(phenylethynyl)-4-[2-(2,5,5-trimethyl-1,3-dioxan-2-yl)ethyl]-2,5-cyclohexadiene-1,4-diol, the 1,2-1,2 adduct.

Provenance & Evidence