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In the presence of a catalytic amount of TsOH or TiCl4, (Z)-5-silyl-4-penten-1-ols ((Z)-1) are smoothly cyclized to 2-silylmethyl-substituted tetrahydrofurans. This cyclization is applicable to the construction of a tetrahydropyran ring. The silyl group and the geometry of the C−C double bond strongly influence the cyclization rate. TBDMS and benzyldimethylsilyl groups considerably accelerate the cyclization in comparison with a dimethylphenylsilyl group, and (E)-vinylsilanes show much lower reactivity than the corresponding (Z)-isomers. The cyclization proceeds by stereospecific syn addition of the hydroxy group. Vinylsilanes 17, 19, and 21, (Z)-5-silyl-4-penten-1-ols bearing a substituent on the methylene tether, smoothly undergo the acid-catalyzed cyclization to give trans-2,5-, cis-2,4-, and trans-2,3-disubstituted tetrahydrofurans, respectively, with moderate to high stereoselectivity. The silyl group of some cyclized products can be easily converted into a hydroxy group with stereochemical retention.

The lateral chromatic aberration from a LiF lens, which is positioned off-axis with respect to the incident light beams, is used to isolate the VUV light generated by the four-wave mixing technique from the intense pump light. The transmittance of the monochromator at the VUV wavelength is limited by the transmittance of a single lens. The ratio of transmitted-to-incident pump energy is 3.3 x 10(-6). A single monochromator with two interchangeable lenses can be used for either tightly focused or collimated pump beams.

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