The synthesis of novel, highly functionalized, C 2-symmetric sulfur-based catalysts is developed and their catalytic applications are explored in asymmetric bromo-, iodo- and seleno-functionalizations of alkenoicacids. This protocol provides the corresponding normal- and medium-sized bromo, iodo and selenolactones in up to 98% yield and 83% stereoselectivity.
开发了新型、高度官能化的 C 2 对称硫基催化剂的合成,并探索了它们在烯酸的不对称溴、碘和硒官能化中的催化应用。该方案以高达 98% 的产率和 83% 的立体选择性提供相应的正常和中等大小的溴、碘和硒内酯。
Copper(II) Acetate-Catalyzed Hydroxysulfenylation-Initiated Lactonization of Unsaturated Carboxylic Acids with Oxygen as Oxidant and Oxygenation Reagent
作者:Bingnan Du、Yang Wang、Haibo Mei、Jianlin Han、Yi Pan
DOI:10.1002/adsc.201700036
日期:2017.5.17
thiols has been explored. The reaction proceeds through a new hydroxysulfenylation-initiated lactonization pathway with carboxyl as electrophilic group, which provides an efficient access to assembly highly valuable thio-substituted lactone derivatives with good yields under mild conditions. Several control experiments, as well as an isotope labelling experiment disclose that oxygen acts as both oxidant
Divergent Access to (1,1) and (1,2)‐Azidolactones from Alkenes using Hypervalent Iodine Reagents
作者:Sébastien Alazet、Franck Le Vaillant、Stefano Nicolai、Thibaut Courant、Jerome Waser
DOI:10.1002/chem.201702599
日期:2017.7.18
versatile synthesis of azidolactones through azidation and cyclization of carboxylic acids onto alkenes has been developed. Based on either photoredox or palladium catalysis, (1,1) and (1,2) azido lactones can be selectively synthesized. The choice of catalyst and benziodoxol(on)e reagent serving as azide source was essential to initiate either a radical or Lewis acid mediated process with divergent
Cobalt-catalyzed oxidative cyclization of gem -disubstituted conjugated alkenols
作者:Tânia M.F. Alves、Mateus O. Costa、Beatriz A.D. Bispo、Fabiana L. Pedrosa、Marco A.B. Ferreira
DOI:10.1016/j.tetlet.2016.06.064
日期:2016.7
Aryl gem-disubstituted conjugated alkenols underwent oxidativecyclization affording 2,5,5-trisubstituted tetrahydrofurans in reasonable yields and good diastereoselectivities using the reductive termination variation of the Mukaiyama aerobic oxidative reaction. Under oxidative termination, the same alkenols produced diols and ketonic by-products via the double hydration and beta-scission competing
Numerous electrophilic thiocyano oxyfunctionalization reactions of alkenes have been achieved using N-thiocyano-dibenzenesulfonimide, which is a newelectrophilic thiocyanation reagent and could be easily prepared in two steps from dibenzenesulfonimide. This approach provides efficient, simple, and modular methods for the formation of SCN-containing heterocycles such as lactones, tetrahydrofurans,