Zirconium-Catalyzed Synthesis of Alkenylaminoboranes: From a Reliable Preparation of Alkenylboronates to a Direct Stereodivergent Access to Alkenyl Bromides
A simple procedure has been optimized for the preparation of alkenylaminoborane from alkynes using diisopropylaminoborane and HZrCp2Cl. Coupled with a magnesium-catalyzed dehydrogenation, it allowed for the use of air- and moisture-stable diisopropylamine. This synthesis has been extended to a one-pot sequence leading directly to bromoalkenes with controlled stereochemistry. As such, it provides an
Treatment of (E)-alk-1-enyldicyclohexylboranes with tributyltin methoxide in the presence of galvinoxyl (1 mol%) at room temperature results in transfer of the alk-1-enyl group from boron to tin to give (E)-alk-1-enyltributylstannanes in a highlystereoselective fashion. Subsequent halodestannylation of (E)-alk-1-enyltributylstannanes is allowed to proceed in a one-pot manner to produce the corresponding
Stereoselective Suzuki−Miyaura Cross-Coupling Reactions of Potassium Alkenyltrifluoroborates with Alkenyl Bromides
作者:Gary A. Molander、Luciana A. Felix
DOI:10.1021/jo050286w
日期:2005.5.1
The stereoselective synthesis of conjugated dienes using air-stable potassium alkenyltrifluoroborates as coupling partners is described. The palladium-catalyzed cross-coupling reaction of potassium (E)- and (Z)-alkenyltrifluoroborates with either (E)- or (Z)-alkenyl bromides proceeds readily with moderate to excellent yields to give the corresponding (E,E)-, (E,Z)-, (Z,E)-, or (Z,Z)-conjugated dienes
描述了使用空气稳定的链烯基三氟硼酸钾作为偶联伴侣的立体选择性合成共轭二烯的方法。钯催化的(E)-和(Z)-烯基三氟硼酸钾与(E)-或(Z)-烯基溴化物的钯催化交叉偶联反应容易进行,产率中等至优异,得到相应的(E,E)- ,(E,Z)-,(Z,E)-或(Z,Z)共轭二烯立体定向。交叉耦合通常可使用5摩尔%的Pd(OAC)的实现2,10摩尔%的PPH 3和Cs的3当量2 CO 3在THF-H 2 O(10∶1)中。两种偶联伙伴均容许多种官能团。
Differential Dihydrofunctionalization: A Dual Catalytic Three‐Component Coupling of Alkynes, Alkenyl Bromides, and Pinacolborane
作者:James E. Baumann、Gojko Lalic
DOI:10.1002/anie.202206462
日期:2022.9.12
differential dihydrofunctionalization of terminal alkynes enables the synthesis of allylic boronate esters through reductive three-component coupling of terminal alkynes, alkenyl bromides, and pinacolborane. The transformation is promoted by cooperative action of a copper/palladium catalyst system and results in hydrofunctionalization of both π-bonds of an alkyne.
The first photo-mediated process enabling the generation of halide radicals by halogen-atom transfer (XAT) is described. This novel reactivity pattern relies on the use of 1,2-dihaloethanes for the generation of unstable carbon radicals by XAT, which after β-scission, release halide radicals that have been used in selective hydrohalogenations of unsaturated hydrocarbons.