In order to obtain information concerning the reaction mechanism of the pyrolysis of sulfonium ylides bearing a substituted phenyl group on the 2-position in the S-ethyl group of ethylphenylsulfonium ylide, (2-phenylethyl)phenylsulfonium bis(methoxycarbonyl)methylide (1) and dicyanomethylide (2) were subjected to pyrolysis in benzene. The reaction rates of 1 and 2 at 140 °C were 6.0- and 3.2-times faster than those of ethylphenylsulfonium bis(methoxycarbonyl)methylide and dicyanomethylide, respectively. The activation parameters for 1 were ΔH‡ = 125 kJ mol−1 and ΔS‡ = −3.8 J K−1 mol−1, while those for 2 were ΔH‡ = 124 kJ mol−1 and ΔS‡ = −2.5 J K−1 mol−1. Substituent effects on the β-phenyl groups in 1 and 2 afforded positive Hammett ρ-values: ρ = 0.49 (γ = 0.997) and ρ = 0.26 (γ = 0.993), respectively. From the obtained results, it was suggested that the pyrolysis proceeds through essentially a concerted intramolecular cis-elimination inclined toward a slightly carbanion-like type from an E1-like type by introducing a phenyl substituent at the 2-position of the ethyl group in the ethylphenylsulfonium ylide.

Despite the reported complete β-selectivity in glycosylation with 2,4-di-O-benzyl-3,6-O-(o-xylylene)glucopyranosyl fluoride, its preparation has been inefficient. This paper describes an improved route for the donor, including the formation of the 3,6-bridge on 1,2,4-orthoacetylglucose, the preparation of which was also refined, along with a discovered feature that the 3,6-bridged glucose prefers the furanose form. Although this feature made the synthesis of the desired glucopyranosyl donor difficult, application of thermal glycosylation solved the problem. With a modifiable intermediate, the improved availability of the donor would expand the applications.

A 1,2-cis-(α)-selective glycosylation has been developed. An ortho-xylylene group bridged between 3-O and 6-O of d-glucosyl fluoride, which straddles the β-face of the pyranose ring, hinders the ­approach of glycosyl acceptors from that face. The determination of the three-dimensional structure of the bridged glucosyl fluoride, the optimization process of the reaction conditions oriented toward kinetic control to realize the high α-selectivity, and the scope of the reaction are described.

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