1-and 2-Naphthols were successfully alkenylated in a regioselective manner by treating the corresponding lithium 1-and 2-naphtholates with magnesium alkylidene carbenoids. The magnesium alkylidene carbenoids were generated in situ by a sulfoxidemagnesium exchange reaction of 1-chlorovinyl 4-tolyl sulfoxides with isopropylmagnesium chloride. The reaction of magnesium alkylidene carbenoids with lithium 2-naphtholates took place at the 1-position of the naphthyl ring to give 1-(alk-1-enyl)-2-naphthols in respectable yields. The alkenylation of 1-naphthols proceeded at the 2-position of the naphthol ring to give 2-(alk-1-enyl)-1-naphthols in yields of 56-67%. In contrast to the reaction of lithium naphtholates with magnesium alkylidene carbenoids, the reaction of lithium phenolates gave low yields of the corresponding alk-1-enyl aryl ethers.

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Melting points were measured using a Yanaco MP-S3 apparatus and are uncorrected. NMR spectra were measured in a CDCl 3 solution using JEOL JNM-LA 300, JEOL JNM-LA 500, Bruker AVANCE DPX 300, and Bruker AVANCE DPX 400 spectrometers. The assignments of the 13 C NMR spectra were made by DEPT 45, 90, and 135. Mass spectra were obtained at 70 eV by direct injection with a HITACHI M-80B mass spectrometer. IR spectra were recorded using a Perkin-Elmer Spectrum One FTIR instrument (KBr or neat) and a Perkin-Elmer Frontier FT-IR spectrometer in the ATR mode. Silica gel 60 N containing 0.5% fluorescence reagent 254 and a quartz column were used in the column chromatography, and the products that absorbed UV light were detected by UV irradiation. Anhydrous THF, α-bromoketones 2b-e, BuLi in hexane, phenyl chloroformate, pyridine, and i-PrMgCl•LiCl in THF were commercially available and used as supplied. Halomethyl p-tolyl sulfoxides 1 and α-bromoketones 2a, 2f, and 2g 2,3 were prepared according to the procedure described in the literature. Diisopropylamine was distilled from CaH 2. All of the reactions involving air-or water-sensitive compounds were routinely conducted in glassware that had been flame-dried under a positive pressure of argon. α-Halobutenolides 5b, 5c, 5d, and 5f are known compounds. 4,5 Characterization data for cyclization precursors 4 and α-halobutenolides 5 (E)-2-[Chloro(p-tolylsulfinyl)methylene]-4-phenylbutyl phenyl carbonate [(E)-4a]