Unsymmetrical 1,1-diborated multisubstituted sp<sup>3</sup>-carbons formed via a metal-free concerted-asynchronous mechanism
作者:Ana B. Cuenca、Jessica Cid、Diego García-López、Jorge J. Carbó、Elena Fernández
DOI:10.1039/c5ob01523e
日期:——
unsymmetrical 1,1-diboration of diazo compounds, formed in situ from aldehydes and cyclic and non-cyclic ketones, in the absence of any transition metal complex. The heterolytic cleavage of the mixed diboron reagent, Bpin–Bdan, and the formation of two geminal C–Bpin and C–Bdan bonds has been rationalised based on DFT calculations to occur via a concerted-asynchronous mechanism. Diastereoselection is attained
I<sub>2</sub>-TBHP-catalyzed one-pot highly efficient synthesis of 4,3-fused 1,2,4-triazoles from N-tosylhydrazones and aromatic N-heterocycles via intermolecular formal 1,3-dipolar cycloaddition
I2-TBHP-catalyzed azomethine imine generation and subsequent regioselective 1,3-dipolarcycloaddition (DC) with aromatic N-heterocycles was developed to afford various 4,3-fused 1,2,4-triazoles in excellent yields. The method is operationally simple and highly efficient with broad functional group tolerance.
Selective C−C Coupling of Vinyl Epoxides with Diborylmethide Lithium Salts
作者:Riccardo Gava、Elena Fernández
DOI:10.1002/chem.201901406
日期:2019.6.18
Vinyl epoxides and styrene oxide can react with diborylmethide lithiumsalts through an exclusive SN2 borylmethylation/ring opening in a regio‐ and diastereoselective way, depending on the nature of the substrate. The ring‐opening protocol provides homoallylboronates that can be transformed into challenging diastereomeric bishomoallylic alicyclic 1,3‐diols. Unprecedented 3‐borylated 1,2‐oxaborolan‐2‐ol
取决于底物的性质,乙烯基环氧化物和苯乙烯氧化物可以通过排他性和非对映选择性的方式,通过专有的S N 2硼甲基化/开环与甲基二硼化锂盐反应。开环方案提供了高烯丙基硼酸酯,可以将其转化为具有挑战性的非对映体双烯丙基烯丙基脂环式1,3-二醇。通过硼甲基化/ 2-甲基-2-乙烯基环氧乙烷的开环,然后进行分子内环化,制备了史无前例的3-硼化的1,2-氧杂硼烷-2-醇产品。
CuI-Catalyzed Cross-Coupling of <i>N</i>-Tosylhydrazones with Terminal Alkynes: Synthesis of 1,3-Disubstituted Allenes
作者:Mohammad Lokman Hossain、Fei Ye、Yan Zhang、Jianbo Wang
DOI:10.1021/jo3024686
日期:2013.2.1
A CuI-catalyzedsynthesis of 1,3-disubstituted allenesfrom1-alkynes by the reaction with various N-tosylhydrazones has been developed. This method, which uses readily available starting materials and is operationally simple, offers 1,3-disubstituted allenes in moderate to good yields. The reaction also tolerates various functional groups.