| Research Abstract |
The followings are new results developed by the present project. 1. Direct synthesis of thiiranes from alkenes using 4,4'-oligothiodimorpholines in the presence of Bronsted acid or metal triflate was investigated. Thus,2-adamantylidene-9-benzonorbornenylidene 1 reacted with 4,4'-teirathiodimorpholine 2, 4,4'-dithiodimorpboline 3, and 4,4'-thiodimorpholine 4 in the presence of carboxylic acid or ptoluenesulfonic acid to give the corresponding thiiranes. When carboxylic acid was used, the rate of reaction was faster as its pK_a value was smaller. Unfortunately, isomerization and decomposition of the resulting thiirane was observed in most of the reactions. Reactivity of 4,4'-oligothiodimorpholiws toward 1 is found to be 2> 3> 4. 2. The direct synthesis of thiiranes using 4,4'-dithiodimorpholine 3 and arid anhydride was investigated. Although reactions of 1 and 3 with highly reactive acid anhydride such as Tf_2O, TfOAc, Ts_2O, and (CF_3C0)_2O took place to form the corresponding thiiranes in moderate yields, their isomerization and decomposition also occurred. The reaction with excess of Ac_2O proceeded to give the thiiranes without the isomerization and decomposition of the products. 2,2'-Biadamantylidene 5, and trans- and cis-cyclooctene, 6 and 7, also reacted to furnish the corresponding thiiranes under the same conditions. 3. The direct synthesis of thiiranes using N, N-dithiobisazoles was investigated. Although the reaction of 1 with N, N-Dithiobisbenzimidazole 8 in the absence of Cu (Otf)_2 and Sc (Otf)_3 did not occur, that with N,N-dithiobis (1H-1,2,4-triazole) 9 proceeded even at-15℃. The alkenes 5-7, norbornene, and anti- and syn-9,9'-bibenzonorbomenylidenes, 8 and 9 also reacted to furnish the corresponding thiiranes with retention of configuration of the alkenes under the same conditions.
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