我们在此报道了外消旋α-硼基甲基-( E )-巴豆基硼酸酯的催化不对称转化。外消旋试剂的布朗斯台德酸催化动力学拆分-烯丙基硼化反应序列在氧化后得到具有高Z选择性和对映选择性的 ( Z )-δ-羟甲基-抗高烯丙醇。同时,利用对映体收敛途径合成了具有优异光学纯度的手性非外消旋1,5-二醇和α,β-不饱和醛。
Transition-Metal-Free Allylic Borylation of 1,3-Dienes
作者:Ricardo J. Maza、Elliot Davenport、Núria Miralles、Jorge J. Carbó、Elena Fernández
DOI:10.1021/acs.orglett.9b00531
日期:2019.4.5
This work explains the reactivity of diboron reagents with 1,3-dienes in a transition-metal-free context. The sole addition of Na2CO3 (30 mol %) to bis(pinacolato)diboron in MeOH allows the 1,4-hydroboration of cyclic and noncyclic 1,3-dienes. The electronic influence on the substrate guarantees the conjugated 1,4-hydroboration versus 1,2-diboration. DFT calculations show that the distribution of charge
这项工作解释了在无过渡金属的情况下乙硼试剂与1,3-二烯的反应性。将Na 2 CO 3(30mol%)仅添加至在MeOH中的双(频哪醇)二硼中,可以使环状和非环状的1,3-二烯进行1,4-氢硼化。电子对底物的影响保证了共轭的1,4-氢硼化与1,2-二硼化。DFT计算表明,烯丙基阴离子中间体中的电荷分布决定着1,4-氢硼化的选择性,而二烯试剂中有利的反式构型决定了对烯丙基硼酸E酯的偏爱。
Diboration of alkenes with bis(pinacolato)diboron catalysed by a platinum(0) complex
Bis(pinacolato)diboron selectively adds to terminal alkenes and cyclic
alkenes having internal strain to provide bis(boryl)alkanes in
76–86% yields in the presence of a catalytic amount of
Pt(dba)
2
at 50 °C.
Synthesis of α-Borylmethyl-(<i>E</i>)-allylborons via Cu-Catalyzed Diboration of 1-Substituted Allenols and Their Application in Stereoselective Aldehyde Allylation
作者:Yeonjoo Lee、Hwiwoong Lee、Yurim Lee、Soohong Cho、Juhyung Lee、Joongoo Kang、Byunghyuck Jung、Yunmi Lee
DOI:10.1021/acscatal.2c06061
日期:2023.2.17
α-borylmethyl-(E)-allylborons was demonstrated by the enantio- and (Z)-selective allylation of aldehydes via Brønsted acid catalysis. Furthermore, (E)-allyl and (E)-homoallyl diols with excellent diastereoselectivity were generated by the Lewisacid catalyzed diastereo- and (E)-selective allyl transfer of (E)-allyldiborons to aldehydes. Using this strategy, the key intermediate in the construction of the C7–C12 fragment
在烯丙基和高烯丙基位置各有一个硼原子的 1,2-二硼具有很大的实用性,尤其是作为双烯丙基化试剂。然而,迄今为止只有少数合成方法被报道,并且底物范围有限。在此,我们开发了 Cu 催化的区域选择性和立体选择性合成 α-硼甲基-( E )-烯丙基硼,从易于获得的 1-取代丙二烯醇和双(频哪醇)二硼。重要的是,这种方法可以高效和区域选择性地形成具有不同取代基的双烯丙基化二硼,否则合成起来会很麻烦,并且可以在克规模上成功进行。α-硼甲基-( E )-烯丙基硼的合成应用通过对映-和( Z)-通过 Brønsted 酸催化对醛进行选择性烯丙基化。此外,通过路易斯酸催化的 ( E )-烯丙基二硼的非对映和 (E)- 选择性烯丙基转移至醛,生成了具有优异非对映选择性的 (E)-烯丙基和( E ) -高烯丙基二醇。使用该策略,还合成了构建(−)-discodermolide 的C 7 –C 12片段的关键中间体。
Catalytic asymmetric transformations of racemic α-borylmethyl-(<i>E</i>)-crotylboronate <i>via</i> kinetic resolution or enantioconvergent reaction pathways
作者:Shang Gao、Jiaming Liu、Ming Chen
DOI:10.1039/d1sc04047b
日期:——
We report herein catalytic asymmetric transformations of racemic α-borylmethyl-(E)-crotylboronate. The Brønsted acid-catalyzed kinetic resolution–allylboration reaction sequence of the racemic reagent gave (Z)-δ-hydroxymethyl-anti-homoallylic alcohols with high Z-selectivities and enantioselectivities upon oxidative workup. In parallel, enantioconvergent pathways were utilized to synthesize chiral nonracemic
我们在此报道了外消旋α-硼基甲基-( E )-巴豆基硼酸酯的催化不对称转化。外消旋试剂的布朗斯台德酸催化动力学拆分-烯丙基硼化反应序列在氧化后得到具有高Z选择性和对映选择性的 ( Z )-δ-羟甲基-抗高烯丙醇。同时,利用对映体收敛途径合成了具有优异光学纯度的手性非外消旋1,5-二醇和α,β-不饱和醛。
Transition-metal-free synthesis of vicinal triborated compounds and selective functionalisation of the internal C–B bond
作者:Elliot Davenport、Elena Fernandez
DOI:10.1039/c8cc06153j
日期:——
1,2,3-Triborated compounds can be prepared by simple nucleophilic borylation of 1,3-dienes, without the assistance of metal catalysts. Selectivefunctionalisation of the internal C–B bond of the 1,2,3-triborated compounds, through cross-coupling with aryl iodides, highlights the powerful methodology toward polyfunctionalisation.