F Thiirane

Epoxypropyloxy)2,2-dinitropropyl azide, 2403 f Ethylene oxide, 0829 f l-Fhioro-2,3-epoxypropane, 1171 Glycidyl azide, 1191 Nitrilotris(oxiranemethane), 3181 f Propylene oxide, 4831 Tetrafluorooxirane, 0632 f Thiirane, 0840... 

Treatment of a carborane derivative of thiirane with A-bromosuccinimide gives a j3-bromodisulfide (79MI50601). Chlorination of CM-2,3-di-f-butylthiirane by f-butyl hypochlorite proceeded differently to the reaction with chlorine itself (Scheme 41) (74JA3146). 

The NMR study of steroidal epoxides (discussed in section II-F) parallels that of the analogous thiiranes. It is possible to relate the location and configuration of the thiirane group with the angular methyl and thiirane proton resonances. The proton NMR relationships for the intermediate thiocyanatohydrins have been included inageneral NMR study of steroids. Electronic spectra may be used in the analysis of steroidal thiiranes. Spectroscopic measurements have shown the existence of a low intensity absorption in the 240-260 m region. The regular patterns of rotatory contributions of thiiranes which are comparable with those of ketones prompted an accumulation of ORD and CD data for steroidal thiiranes. 

The elimination of sulfur dioxide from thiirane dioxides leading to the corresponding alkenes is not the only result of base-induced reactions other products are also formed. This fact raises the question of the mechanistic pathway of this reaction. In general, the thiirane dioxide is treated with a large excess of the base in an appropriate solvent for several hours at room temperature or below. Bases commonly used are 2n NaOH (in water), NaOCH3 (in methanol), t-BuO-K + (in f-BuOH) and BuLi (in tetrahydrofuran) or KOH-CCU (in t-BuOH)16-19"112 113. 

Fujisawa, T. Kobori, T. Chem. Lett., 1972, 935. For another method of alkene-thiirane conversion, see Capozzi, F. Capozzi, G. Menichetti, S. Tetrahedron Lett., 1988, 29, 4177. 

Significantly, (a) a-sulfonyl carbanions of thiirane dioxides, generated from the latter in the presence of strong bases such as potassium f-butoxide and alkoxide ions , do epimerize to relieve steric repulsion between substituents as in 42 above and (b) the a-hydrogen in aryl-substituted three-membered sulfoxides (e.g. 46c) are sufficiently acidic to... 

When thiocarbonyl and ot-diazocarbonyl compounds are combined, acyl-substituted thiocarbonyl ylides 158 are generated from a nonisolable 3-acyl-1,2,4-thiadiazoline 157 (Scheme 8.36). In addition to giving acylthiiranes 159 and 1,3-dithiolanes 160, dipoles 158 can also 1,5-cyclize to produce 1,3-oxathioles 161. Acyl-thiocarbonyl ylides derived from diazoketones [e.g., HC(0)C(N2)R, R = Ph, f-Bu (219,220) 2-diazocyclohexanone (221)] produce 1,3-oxathioles [e.g., 162 (220), Scheme 8.36], while those derived from diazoesters (218,222,223) lead to thiiranes by 1,3-cyclization. Ylides derived from a-diazocarboxamides form 1,3-oxathioles (e.g., 163) and thiiranes (e.g., 159, R = f-Bu, R = NMePh, R = R" = Ph), depending on the nature of the substituents (220). A related 1,5-cyclization of an aminomethyl-thiocarbonyl ylide formed from dimethyl 3-anilino-2-diazobutanedioate was also reported (224). 

Ethylene glycol monomethyl ether, see 2-Methoxyethanol, 1280 f Ethylene sulfide, see Thiirane, 0836... 

Three membered rings are all strained and the parent systems may be endothermic (AH°f. cyclopropane 35 oxirane -78 aziridine 92 thiirane 52 kJ/mole). Some molecules with small distorted rings (of high strain energy) are explosively unstable. Individual entries are ... 

Simulated annealing calculations were performed to acquire the mechanisms of thermolysis of thiirane and thiiranium cation <2002JMT71>. The AMPAC 6.55 package along with AIMl and SAMI methods were used to estimate structures, which were then used as starting points for further ab initio calculations. Critical points were confirmed by calculation of the vibrational frequencies. The primary reactions thiirane 19 —> S-f ethene, thiirane—> vinyl thiol 20, and thiirane ethanethial (thioacetaldehyde) 21 were examined for thermolysis of thiirane Scheme 1. Many secondary reactions were also examined. The simulated annealing method was predicted to be very useful in the future for the study of competing chemical reactions. 

A fast-mixing nozzle in an FT microwave spectrometer was used to measure rotational constants, centrifugal distortion constants, Cl-nuclear quadrupole- and spin-rotational coupling constants for the isotopomers (CH2)2S- C1F and (CH2)2S- C1F <1996CPL119>. The complex, with symmetry, has an arrangement of the S-CIF nuclei that is about 3.5° off collinearity. The Cl-F axis makes an angle of 95° with thiirane s C-2 axis. 

Very rapid desulfurization of thiiranes by a bimetallic complex was reported late in 1995. Bergman and co-workers found that Cp2Zr(/t-A -f-Bu)IrCp, where Cp is cyclopentadienyl and Cp is pentamethylcyclopenta-dienyl, desulfurizes thiiranes via a bridging sulfido complex 121, for which a crystal structure was obtained <1995JA10041>. Small substituent effects in the thiiranes and retention of substituent stereochemistry suggested that ring-opened intermediates are not involved and that the reaction rate might approach the diffusion-controlled limit. 

Replacement of disulfur dichloride by sulfur dichloride in reaction with acetylenes in dichloromethane led to formation of 2,3-dichlorothiiranes in quantitative yield <2001TL4017>. Acid hydrolysis of 2,3-dichlorothiirane (R = R = f-Bu) gave a mixture of 2,2,5,5-tetramethyl-4-oxo-3-hexanethione 289 and 2,3-di-f-butylthiirene-l-oxide 290 (Scheme 83). Exclusive formation of thiirene-A-oxides was observed during alkaline hydrolysis of 2,3-dichloro thiiranes. 

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