Cyclization and Ring-Expansion Processes Involving Samarium Diiodide Promoted Reductive Formation and Subsequent Oxidative Ring Opening of Cyclopropanol Derivatives
convert to cyclic conjugated enones in moderate to good yields. In addition, the reduction−oxidation reaction sequences can be successfully performed in one pot. The regioselectivities of cyclopropane ringopening in the bicyclic substrates depend on the oxidizing agents used. For example, reactions promoted by FeCl3 with pyridine lead to the expected ring-expansion process involving internal-bond cleavage
io二碘化物促进了各种α-溴甲基环烷酮的反应,然后用三甲基甲硅烷基氯进行处理,导致嵌在双环[ m .1.0]烷烃骨架中的环丙基甲硅烷基醚的生产。用氧化性电子转移试剂(例如Fe(III),Ce(IV)和Mn(III)盐)处理醚时,会生成扩环酮,并以中等至良好的产率转化为环状共轭烯酮。另外,还原氧化反应序列可以在一锅中成功进行。双环底物中环丙烷开环的区域选择性取决于所用的氧化剂。例如,FeCl 3促进的反应用吡啶导致预期的扩环过程,该过程涉及双环烷烃的内部键裂解并产生环烯酮作为最终产物。相反,与Ce(NH 4)2(NO 3)6或Mn(OAc)3作为氧化剂的反应通过外键裂解进行,得到α-碘甲基环烷酮。
Tris(trimethylsilyl)silane promoted radical reaction and electron-transfer reaction in benzotrifluoride
Tris(trimethylsilyl)silane (TTMSS) promoted free radical reaction in benzotrifluoride (BTF) was investigated. Compared to same reaction using environmentally less desirable tri-n-butyltin hydride (TBTH) in benzene, less quantity of BTF than that of benzene can be used because of slower hydrogen atom transfer from TTMSS than that from TBTH toward primary alkyl radicals. Also, electron-transfer reactions
observed solvent effects that govern the reaction pathways followed are a consequence of varying solvation of copper intermediates, which governs their reactivity and redox properties. In addition, the influence of counteranions of the copper salts, organonitriles, cyclic dienes, and substrate structures on the pathways followed in these reactions was also examined.
utilized to promote the oxidative ring-opening reaction of cyclopropyl silyl ethers giving ring-expanded ketones. Exploration of salt quantity effect on the reaction allowed us to hypothesize that amine radical cation is regenerated through the oxidation of neutral amine by hexachloroantimonate anion. Based on this hypothesis, amine radical cation was initially generated by the treatment of parent amine
Oxidative ring-opening reactions of cyclopropyl silyl ethers incorporated into bicyclo[m.1.0]alkane framework were investigated. The results show that the regioselectivities for ring-opening of intermediate radical cations, formed by single electron transfer, are governed by the nature of the nucleophile as well as oxidizing species.