Methoxymethyl-triphenylphosphonium chloride → 2-(2-Methoxy-1-methyl-vinyl)-3-methyl-5-(4-trifluoromethyl-phenyl)-thiophene

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Reaction Steps

To a solution of (methoxymethyl)triphenyl phosphonium chloride (3.96 g, 10.76 mmole) in toluene/THF (2:1, 60 mL), is added potassium t-butoxide (1.21 g, 10.76 mmole) in one portion and stirred for 30 minutes. To the resulting ylide, is injected into a solution of 1-[3-Methyl-5-(4-trifluoromethyl-phenyl)-thiophen-2-yl]-ethanone (1.53 g, 5.38 mmole). The reaction is stirred for 2 hours, and then concentrated on rota vapor. The residue is purified on a silica gel column, eluting with 0-10% ethyl acetate in hexane and concentrated to provide 2-(2-Methoxy-1-methyl-vinyl)-3-methyl-5-(4-trifluoromethyl-phenyl)-thiophene as brown oil. The generated vinyl ether is treated with concentrated HCl(aq) (2 mL) in THF (60 mL) at 60° C. for 2 hours. The solvents are removed on rota vapor, and the residue is purified on a silica gel column, eluting with 0-20% ethyl acetate in hexane and concentrated to provide the titled compound as colorless oil.

Provenance & Evidence