Palladium-Catalyzed Cross-Coupling Reaction of Bis(pinacolato)diboron with 1-Alkenyl Halides or Triflates: Convenient Synthesis of Unsymmetrical 1,3-Dienes via the Borylation-Coupling Sequence
1-alkenylboronic acid pinacol esters via a palladium-catalyzed cross-coupling reaction of bis(pinacolato)diboron (pin(2)B(2), pin = Me(4)C(2)O(2)) with 1-alkenyl halides or triflates was carried out in toluene at 50 degrees C in the presence of KOPh (1.5 equiv) and PdCl(2)(PPh(3))(2)-2Ph(3)P (3 mol %). The borylation of acyclic and cyclic 1-alkenyl bromides and triflates was achieved in high yields with complete
Coumarins by Direct Annulation: β‐Borylacrylates as Ambiphilic C
<sub>3</sub>
‐Synthons
作者:Max Wienhold、John J. Molloy、Constantin G. Daniliuc、Ryan Gilmour
DOI:10.1002/anie.202012099
日期:2021.1.11
2‐halo‐phenol derivatives to generate structurally and electronically diverse coumarins. Key to this [3+3] disconnection is the BPin unit which serves a dual purpose as both a traceless linker for C(sp2)–C(sp2) coupling, and as a chromophore extension to enable inversion of the alkene geometry via selective energy transfer catalysis. Mild isomerisation is a pre‐condition to access 3‐substituted coumarins
Palladium(0)-Mediated Rapid Methylation and Fluoromethylation on Carbon Frameworks by Reacting Methyl and Fluoromethyl Iodide with Aryl and Alkenyl Boronic Acid Esters: Useful for the Synthesis of [<sup>11</sup>C]CH<sub>3</sub>C- and [<sup>18</sup>F]FCH<sub>2</sub>C-Containing PET Tracers (PET=Positron Emission Tomography)
methylation and fluoromethylation on aryl and alkenyl frameworks by using methyl and fluoromethyl iodide with an organoboronic acid ester has been developed under the simple and mild conditions of [Pd2(dba)3]/P(o‐CH3C6H4)3/K2CO3 (dba= dibenzylideneacetone) in DMF at 60 °C for 5 min (see scheme). This boron protocol provides a firm chemical basis for the synthesis of 11C‐ and 18F‐incorporated PET tracers.
在简单温和的 [Pd 2 (dba) 3 ]/P( o ‐CH )条件下,开发了一种新的合成方法,利用甲基和氟甲基碘与有机硼酸酯在芳基和烯基骨架上进行快速甲基化和氟甲基化3 C 6 H 4 ) 3 /K 2 CO 3 (dba=二亚苄基丙酮)在DMF中在60°C下5分钟(参见方案)。该硼方案为合成11 C 和18 F 的 PET 示踪剂提供了坚实的化学基础。
Copper(II)-Catalyzed β-Borylation of Acetylenic Esters in Water
作者:Webster Santos、Cheryl Peck、Joseph Calderone
DOI:10.1055/s-0034-1380524
日期:——
presence of bis(pinacolato)diboron and catalytic amounts of both copper(II) and 4-picoline, substituted alkynoates undergo borylation in a regio-, stereo-, and chemoselective fashion. The reaction is performed under mild conditions using water as solvent and open to the atmosphere to exclusively afford (Z)-β-boryl-α,β-unsaturated esters. A method for the β-borylation of alkynoates has been developed
Phosphine–copper(I) complexes efficiently catalyzed the mono-boration of electron-deficient alkynes in the presence of MeOH and also catalyzed conjugate reductions of alkenylboronates bearing an electron-withdrawing group. The mono-addition of bis(pinacolato)diboron to alkynes catalyzed by a copper–Xantphos complex produced vinylboronates with high regio and stereoselectivity and asymmetric reduction