Palladium-catalysed regio- and stereoselective arylative substitution of γ,δ-epoxy-α,β-unsaturated esters and amides by sodium tetraaryl borates
作者:Yasemin Bilgi、Melih Kuş、Levent Artok
DOI:10.1039/d0ob01226b
日期:——
Palladium-catalysed reactions of γ,δ-epoxy-α,β-unsaturated esters and amides with NaBAr4 reagents proceeded regio- and stereoselectively, producing allylic homoallyl alcohols with aryl-substituents in the allylic position for a wide range of substrates. AsPh3 was found to be a competent ligand for the arylation reaction, whereas phosphine ligand/Lewis acidic organoboron combinations favoured the substitution
Direct Formic Acid Mediated
<i>Z</i>
‐Selective Reductive Coupling of Dienes and Aldehydes
作者:Christopher Cooze、Raphael Dada、Rylan J. Lundgren
DOI:10.1002/anie.201905540
日期:2019.8.26
carbonyls to generate Z-olefin products remain rare and often require either alkyl borane or zinc reductants, limiting their utility. Demonstrated here is that formic acidmediates the Rh-catalyzed, Z-selective coupling of dienes and aldehydes. The process is distinguished by broad tolerance towards reducible or electrophilic groups. Kinetic analysis suggests that generation of the catalytically active
Steric Hindrance Drives the Boron‐Initiated Polymerization of Dienyltriphenylarsonium Ylides to Photoluminescent C5‐Polymers
作者:Xin Wang、Nikos Hadjichristidis
DOI:10.1002/anie.202109190
日期:2021.10.4
A series of alkyl-subsituted dienyltriphenylarsoniumylides were synthesized and used as monomers in borane-initiated polymerization to obtain practically pure C5-polymers (main-chain grows by five carbon atoms at a time). The impact of triethylborane (Et3B), tributylborane (Bu3B), tri-sec-butylborane (s-Bu3B), and triphenylborane (Ph3B) initiators on C5polymerization was studied. Based on NMR and
合成了一系列烷基取代的二烯基三苯基胂叶立德,并将其用作硼烷引发聚合的单体,以获得几乎纯的C5聚合物(主链一次增长五个碳原子)。研究了三乙基硼烷(Et 3 B)、三丁基硼烷(Bu 3 B)、三仲丁基硼烷( s -Bu 3 B)和三苯基硼烷(Ph 3 B)引发剂对C5聚合的影响。基于 NMR 和 SEC 结果,我们表明所有合成的聚合物都具有具有独特不饱和主链的 C5 单元,其中两个共轭双键被一个亚甲基分隔。合成的C5聚合物具有可预测的分子量和窄的分子量分布( M n,NMR =2.8 −11.9 kg mol −1 , Ð =1.04–1.24)。研究发现,增加单体和引发剂的空间位阻可以促进更多C5重复单元的形成,从而驱动聚合反应形成几乎纯的C5聚合物(高达95.8%)。通过11 B NMR 研究了聚合机理,并通过 DFT 计算证实了聚合机理。合成的C5聚合物是无定形的,通过调节单体的取代基可调节玻璃化转变温度,范围为+30
Iron-catalyzed δ-selective conjugate addition of methyl and cyclopropyl Grignard reagents to α,β,γ,δ-unsaturated esters and amides
Iron-catalyzed δ-selective conjugate addition of methyl and cyclopropyl Grignardreagents to α,β,γ,δ-unsaturated esters and amides took place in good yields to give products exclusively with cis-β,γ-olefinic bond.