Regioselective Arylboration of Isoprene and Its Derivatives by Pd/Cu Cooperative Catalysis
作者:Kevin B. Smith、M. Kevin Brown
DOI:10.1021/jacs.7b04024
日期:2017.6.14
A method for the regioselective arylboration of isoprene and its derivatives is presented. These reactions allow for the synthesis of useful building blocks from simple components. Through these studies, an unusual additive effect with DMAP has been uncovered that allows for altered reactivity and the formation of quaternary carbon centers. The utility of this method is demonstrated toward the formal
Enantioselective Palladium-Catalyzed Alkenylation of Trisubstituted Alkenols To Form Allylic Quaternary Centers
作者:Harshkumar H. Patel、Matthew S. Sigman
DOI:10.1021/jacs.6b09649
日期:2016.11.2
In this report, we describe the generation of remote allylic quaternary stereocenters β, γ, and δ relative to a carbonyl in high enantioselectivity. We utilize a redox-relay Heck reaction between alkenyl triflates and acyclic trisubstituted alkenols of varying chain-lengths. A wide array of terminal (E)-alkenyl triflates are suitable for this process. The utility of this functionalization is validated
Chemo- and stereoselectivity in the ring-openingreaction of epoxides with a reagent prepared from allylmagnesium halide and chlorotitanium triphenoxide is described. It has been proven that the allylating reagent can also be used for the reaction of epoxides bearing a tert-butyl ester, amide, or acetal moiety, and that the epoxide cleavage regioselectively takes place at the more substituted carbon
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。
Rearrangement Reactions Leading to Optically Active α,α-Disubstituted Primary Allylamines
Syntheticroutes to α,α-disubstituted allylamines have been examined. Racemic compounds were conveniently prepared by thermal Overman rearrangements of primary allyl alcohols with trisubstituted double bonds, but rearrangement of these substrates by the only commercially available compound known to catalyze enantioselective Overman rearrangements, the cobalt oxazoline palladacycle (R)-COP-Cl, failed