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The (2 + 2)- and (4 + 2)-cycloaddition of triplet xanthenethione to phenyl-, methoxy-tert-butoxy-, (methylthio)-, (tert-butylthio)- and 1,1-dimethyl-allene gives rise to thietanes 3 and 4, and to thiopyran derivative 5, respectively. The mechanism of the reaction is discussed. In the case of thietane 3 (X = Ph), prototropy to the stable thiete 6 has been observed.

α,β-Unsaturated thioamides and vinylogous thioamides have been prepared by thermal addition of trithiocarbonates RS-C(S)SR1 to 1-(diethylamino)propyne. Aromatic dithio esters Ar-C(S)SR only gave the α,β-unsaturated thioamides. The dithio ester Me2CH-C(S)SMe adds as acidic enethiol tautomer Me2CC(SH)SMe to 1-(diethylamino)propyne. Reaction mechanisms and the stereochemistry of the adducts are discussed.

A modified synthetic route to 1,2,3-butatrienyl ethers 3 is presented. It involves hydroxyalkylation of 2-propynyl ethers with an aldehyde or a ketone, followed by trimethylsilylation of the hydroxy ether 1 and 1,4-elimination of Me3SiOH from 2 with ethyllithium.

An electron microprobe interdiffusion study was made in single crystals between 1200° and 1331°C over the solid-solution compositional range 0 to 20 mol% YF3 in CaF2. At constant temperature, the value of δ, the interdiffusion coefficient, increased approximately exponentially with increasing YF3 content. As YF3 content increased, the temperature dependence of δ decreased. Extrapolation of δ to 0% YF3 combined with consideration of the defect formation mechanism at mite dilution allowed estimation of the impurity diffusion coefficient for Y in essentially pure CaF2.

Tertiary acetylenic alcohols have been transformed into the O-trimethylsilyl derivatives with trimethylsilyl chloride and triethylamine, using catalytic amounts of dimethyl sulfoxide, hexamethylphosphoric triamide, imidazole, or 1,5-diazabicyclo[5.4.0]undec-5-ene. Saturated tertiary alcohols can be trimethylsilylated in the same way.

A modified synthetic route to 1,2,3-butatrienyl ethers 3 is presented. It involves hydroxyalkylation of 2-propynyl ethers with an aldehyde or a ketone, followed by trimethylsilylation of the hydroxy ether 1 and 1,4-elimination of Me3SiOH from 2 with ethyllithium.

The (2 + 2)- and (4 + 2)-cycloaddition of triplet xanthenethione to phenyl-, methoxy-tert-butoxy-, (methylthio)-, (tert-butylthio)- and 1,1-dimethyl-allene gives rise to thietanes 3 and 4, and to thiopyran derivative 5, respectively. The mechanism of the reaction is discussed. In the case of thietane 3 (X = Ph), prototropy to the stable thiete 6 has been observed.

α,β-Unsaturated thioamides and vinylogous thioamides have been prepared by thermal addition of trithiocarbonates RS-C(S)SR1 to 1-(diethylamino)propyne. Aromatic dithio esters Ar-C(S)SR only gave the α,β-unsaturated thioamides. The dithio ester Me2CH-C(S)SMe adds as acidic enethiol tautomer Me2CC(SH)SMe to 1-(diethylamino)propyne. Reaction mechanisms and the stereochemistry of the adducts are discussed.

Tertiary acetylenic alcohols have been transformed into the O-trimethylsilyl derivatives with trimethylsilyl chloride and triethylamine, using catalytic amounts of dimethyl sulfoxide, hexamethylphosphoric triamide, imidazole, or 1,5-diazabicyclo[5.4.0]undec-5-ene. Saturated tertiary alcohols can be trimethylsilylated in the same way.