Development of a Palladium-Catalyzed Process for the Synthesis of<i>Z</i>-Alkenes by Sequential Sonogashira-Hydrogenation Reaction
作者:Sören Hancker、Helfried Neumann、Matthias Beller
DOI:10.1002/ejoc.201800651
日期:2018.10.17
A selective one‐pot protocol for the synthesis of Z‐alkenes via Sonogashira–semihydrogenation is reported. In this process the original homogeneous palladium catalyst is transformed into an active heterogeneous material.
Copper-catalysed, diboron-mediated <i>cis</i>-dideuterated semihydrogenation of alkynes with heavy water
作者:Xiaowei Han、Jiefeng Hu、Cheng Chen、Yu Yuan、Zhuangzhi Shi
DOI:10.1039/c9cc03213d
日期:——
efficiently mediate the transfer of two D atoms from heavy water directly onto alkynes through copper-catalysed cis-selective semihydrogenation. Avoiding the use of costly and flammable D2 gas, this safe and practical process can proceed with excellent chemoselectivity and stereoselectivity. Utilizing the present method as the key step, the formal asymmetrictotalsynthesis of d2-deuterium-labeled cis-combretastatin
protonolysis of the Ir–C(vinyl) bond. Instead, mechanistic data are consistent with an anion-involved alcoholysis pathway involving ionization of (NCP)IrCl(vinyl) via EtOH-for-Cl substitution and reversible protonation of Cl– ion with an Ir(III)-bound EtOH, followed by β-H elimination of the ethoxy ligand and C(vinyl)–H reductive elimination. The use of an amine is key to the monohydride mechanism by promoting
Reduction of titanocene dichloride with dysprosium: access to a stable titanocene(<scp>ii</scp>) equivalent for phosphite-free Takeda carbonyl olefination
A new titanocene(ii) equivalent obtained from the reduction of titanocene dichloride with dysprosium allows phosphite-free and simplified Takeda carbonyl olefination reactions.
<i>Z</i>-Stereoselective Aza-Peterson Olefinations with Bis(trimethylsilane) Reagents and Sulfinyl Imines
作者:Manas Das、Donal F. O’Shea
DOI:10.1021/acs.orglett.5b03519
日期:2016.1.15
Highlystereoselective aza-Peterson olefinations from bench-stable α,α-bis(trimethylsilyl)toluene reagents and N-substituted imines have been achieved using TMSO–/Bu4N+ as Lewis base activator in THF. Remarkably, and for the first time, N-t-butanesulfinyl imines were utilized for the synthesis of Z-stilbenes with excellent selectivities, while N-aryl imines generated E-stilbenes under identical reaction