Direct Synthesis of Thiiranes from Alkenes Using Diaminoligosulfane and Acid Catalyst

点击翻译按钮获取中文摘要

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.