Enantioselective NHC‐Catalyzed Redox [2+2] Cycloadditions with Perfluoroketones: A Route to Fluorinated Oxetanes
作者:Alyn T. Davies、Alexandra M. Z. Slawin、Andrew D. Smith
DOI:10.1002/chem.201504256
日期:2015.12.21
carbene (NHC) catalyzedredox formal [2+2] cycloaddition between α‐aroyloxyaldehydes and perfluoroketones, followed by ring‐opening in situ delivers a variety of perfluorinated β‐hydroxycarbonyl compounds in good yield, and excellent diastereo‐ and enantioselectivity. Through a reductive work‐up and subsequent cyclization, this protocol offers access to highly substituted fluorinatedoxetanes in two
Catalytic enantioselective synthesis of perfluoroalkyl-substituted β-lactones <i>via</i> a concerted asynchronous [2 + 2] cycloaddition: a synthetic and computational study
作者:Diego-Javier Barrios Antúnez、Mark D. Greenhalgh、Alexander C. Brueckner、Daniel M. Walden、Pilar Elías-Rodríguez、Patrick Roberts、Benjamin G. Young、Thomas H. West、Alexandra M. Z. Slawin、Paul Ha-Yeon Cheong、Andrew D. Smith
DOI:10.1039/c9sc00390h
日期:——
The enantioselective preparation of a range of perfluoroalkyl-substituted β-lactones through an isothiourea (HyperBTM) catalysed reaction using symmetric anhydrides as ammonium enolate precursors and perfluoroalkylketones (RF = CF3, C2F5, C4F9) is reported. Following optimisation, high diastereo- and enantioselectivity was observed for β-lactone formation using C2F5- and C4F9-substituted ketones at
据报道,使用对称酸酐作为烯醇酸铵前体和全氟烷基酮(R F = CF 3,C 2 F 5,C 4 F 9),通过异硫脲(HyperBTM)催化反应对映选择性地制备了一系列全氟烷基取代的β-内酯。优化后,在室温下使用C 2 F 5和C 4 F 9取代的酮可观察到高非对映选择性和对映选择性(26个实例,最高> 95:5 dr和> 99:1 er) ,而对于CF 3而言,最佳的dr和er需要−78°C取代的酮(11个实例,最大> 95:5 dr和> 99:1 er)。通过开环衍生化β-内酯,以及两步转化生成全氟烷基取代的氧杂环丁烷,已证明在不损失立体化学完整性的情况下。密度泛函理论计算与13 C自然丰度KIE研究一起,已被用于通过一致的异步[2 + 2]-环加成途径来探索反应机理,该途径优于逐步的羟醛-内酯化过程。
Process for the preparation of aryl perfluoroalkyl ketones
申请人:Hoechst Aktiengesellschaft
公开号:US04835318A1
公开(公告)日:1989-05-30
A process for the preparation of arylperfluoroalkyl ketones of the general formula I ##STR1## wherein R.sup.1 and R.sup.5 represent at least one of the substituents hydrogen, halogen, alkyl, alkoxy, alkylthio and perfluorinated alkyl, each having from 1 to 6 carbon atoms and n is an integer from 1 to 6, which comprises reacting an aryl carbonyl compound having the general formula II ##STR2## wherein R.sup.1 to R.sup.5 have the above-mentioned meaning and X as a monovalent moiety represents fluorine, chlorine or bromine and as a bivalent moiety the oxygen atom of an anhydride bridge, with a perfluoroalkyl halide of the general formula C.sub.n F.sub.2n+1 -Hal (III), wherein Hal represents chlorine, bromine or iodine and n is an integer from 1 to 6, in the presence of a trisdialkyl amide of phosphorus acid of the general formula P[N(alkyl)2]3 (IV).
A Desilylative Approach to Alkyl Substituted C(1)‐Ammonium Enolates: Application in Enantioselective [2+2] Cycloadditions
作者:Yihong Wang、Claire M. Young、Honglei Liu、Will C. Hartley、Max Wienhold、David. B. Cordes、Alexandra M. Z. Slawin、Andrew D. Smith
DOI:10.1002/anie.202208800
日期:2022.9.19
The catalytic generation of unsubstituted and alkylsubstituted C(1)-ammonium enolates from α-silyl-α-alkyl substituted carboxylic acids using the isothiourea HyperBTM has been developed and applied in enantioselective [2+2]-cycloaddition reactions.