Bridging the Final Gap in Stereocontrolled Wittig Reactions: Methoxymethoxy-Armed Allylic Phosphorus Ylides Affording Conjugated Dienes with Highcis Selectivity
sodium amide), 2-alkenyltris(2-methoxymethoxyphenyl)phosphonium salts carrying an allyl, crotyl, or prenyl (3-methyl-2-butenyl) side chain condense with saturated or unsaturated aldehydes to give conjugated dienes with Z/E ratios ranging from 90:10 to > 99:1 and averaging 96:4. Owing to steric congestion, yields are only moderate (on average 41%; extremes 10-79%). The nonvolatile tris(2-methoxymethoxyphenyl)phosphine
An efficient nickel-catalyzed regioselective hydroarylation of 1,3-dienes with arylhalides and using silanes as hydride source is developed, affording functionalized arenes in good to excellent yields under mild conditions. The protocol shows a high tolerance to various functional groups on both the dienes and aryl coupling partners. Mechanism studies indicate that π-allyl nickel species is likely
Catalyst Controlled Regiodivergent Arylboration of Dienes
作者:Stephen R. Sardini、M. Kevin Brown
DOI:10.1021/jacs.7b05477
日期:2017.7.26
A method for the regiodivergent arylboration of dienes is presented. These reactions allow for the formation of a diverse range of synthetically versatile products from simple precursors. Through mechanistic studies, these reactions likely operate by initial addition of a Cu-Bpin complex across the diene followed by Pd-catalyzed cross coupling with an aryl halide or pseudohalide.
Ni-Catalyzed Site-Selective Dicarboxylation of 1,3-Dienes with CO<sub>2</sub>
作者:Andreu Tortajada、Ryo Ninokata、Ruben Martin
DOI:10.1021/jacs.7b13220
日期:2018.2.14
A site-selective catalytic incorporation of multiple CO2 molecules into 1,3-dienes en route to adipic acids is described. This protocol is characterized by its mildconditions, excellent chemo- and regioselectivity and ease of execution under CO2 (1 atm), including the use of bulk butadiene and/or isoprene feedstocks.
描述了一种位点选择性催化将多个 CO2 分子结合到 1,3-二烯到己二酸的过程中。该协议的特点是条件温和,具有出色的化学和区域选择性,并且在 (1 atm) 下易于执行,包括使用散装丁二烯和/或异戊二烯原料。
Aqueous Wittig reactions of semi-stabilized ylides. A straightforward synthesis of 1,3-dienes and 1,3,5-trienes
作者:James McNulty、Priyabrata Das
DOI:10.1016/j.tetlet.2009.07.133
日期:2009.10
A direct synthesis of 1,3-dienes and 1,3,5-trienes from the reaction of semi-stabilized ylides and a range of saturated and unsaturated aldehydes is reported in water as solvent, employing sodium hydroxide as base. The water-soluble phosphine oxide side product is removed simply by aqueous partitioning of the organic products.