Regioselective Allene Synthesis and Propargylations with Propargyl Diethanolamine Boronates
摘要:
The utility of propargyl diethanolamine boronates as reagents for the preparation of allenes and homopropargylic alcohols is presented. Protonolysis with TFA and electrophilic substitution with N-halosuccinimides proceeded with inversion to provide the corresponding allene in high yield and regioselectivity. Alternatively, the propargylation of aldehydes was achieved with use of the in situ generated lithiated complex.
Palladium-catalyzed Cycloaddition of Alkynyl Aryl Ethers to Allenes to Form a 2,3-Bismethylidene-2,3-dihydro-4<i>H</i>-1-benzopyran Framework
作者:Yasunori Minami、Mayuko Kanda、Tamejiro Hiyama
DOI:10.1246/cl.130894
日期:2014.2.5
Palladium-catalyzed cycloaddition of alkynyl aryl ethers to allenes proceeds through o-C–H activation to give 2,3-dihydro-4H-1-benzopyran derivatives containing 2,3-exo-double bonds. These benzopyr...
An oxidative allylation process mediated by a hypervalent iodine reagent has been performed on polysubstituted phenols. This reaction, occurring in useful to good yields, leads to a rapid access to dienones containing a quaternary carbon center.
Copper(I)-Catalyzed Regio- and Chemoselective Single and Double Addition of Nucleophilic Silicon to Propargylic Chlorides and Phosphates
作者:Chinmoy K. Hazra、Martin Oestreich
DOI:10.1021/ol301827t
日期:2012.8.3
Copper(I)-catalyzed propargylic substitution of linear precursors with (Me2PhSi)2Zn predominantly yields the γ isomer independent of the propargylic leaving group. The thus formed allenylic silane reacts regioselectively with another equivalent of (Me2PhSi)2Zn, yielding a bifunctional building block with allylic and vinylic silicon groups. The reaction rates of both steps are well-balanced for chloride
Chromium‐Catalyzed Selective Dimerization/Hydroboration of Allenes to Access Boryl‐Functionalized Skipped (
<i>E</i>
,
<i>Z</i>
)‐Dienes
作者:Yinsong Zhao、Shaozhong Ge
DOI:10.1002/anie.202012344
日期:2021.1.25
dimerization/hydroboration of allenes is developed to access synthetically versatile boryl‐functionalized skippeddienes with a catalyst generated in situ from CrCl2 and a pyridine‐2,6‐diimine ligand mesPDI. A variety of allenes reacted with pinacolborane (HBpin) to afford the corresponding boryl‐functionalized (E,Z)‐1,4‐dienes in high yields and with excellent selectivity. Electron paramagnetic resonance (EPR) spectroscopic
Cobalt‐Catalyzed Regio‐ and Stereoselective Hydroboration of Allenes
作者:Can Li、Zheng Yang、Lei Wang、Yinlong Guo、Zheng Huang、Shengming Ma
DOI:10.1002/anie.201915716
日期:2020.4.6
pincer-ligand-based cobalt-complex-catalyzed allenehydroboration affording Z-allylic boronates is described. The reaction demonstrates an excellent regio- as well as Z-stereoselectivity and a wide substrate scope that tolerates many functional groups. Based on solvent-assisted electrospray ionization mass spectrometry (SAESI-MS) studies, a rationale for the cobalt-catalyzed hydroboration involving the highly selective