Rhodium(III)-Catalyzed Redox-Neutral Coupling of<i>N</i>-Phenoxyacetamides and Alkynes with Tunable Selectivity
作者:Guixia Liu、Yangyang Shen、Zhi Zhou、Xiyan Lu
DOI:10.1002/anie.201300881
日期:2013.6.3
Give it a tweak: A novel oxidizing directing group was developed for a rhodium(III)‐catalyzed CH functionalization of N‐phenoxyacetamides with alkynes. A small change in the reaction conditions leads to either ortho‐hydroxyphenyl‐substituted enamides or cyclization to deliver benzofurans with high selectivity (see scheme; Cp*=C5Me5).
给它一个调整:一种新颖的氧化定向基团被用于铑(III)催化的开发Ç h的官能Ñ与炔-phenoxyacetamides。反应条件的微小变化会导致邻-羟苯基取代的酰胺或环化反应以高选择性提供苯并呋喃(参见方案; Cp * = C 5 Me 5)。
Decarboxylative Suzuki–Miyaura coupling of (hetero)aromatic carboxylic acids using iodine as the terminal oxidant
作者:Jacob M. Quibell、Guojian Duan、Gregory J. P. Perry、Igor Larrosa
DOI:10.1039/c9cc01817d
日期:——
of (hetero)aromaticcarboxylicacids with arylboronic acids. The scope of this decarboxylative Suzuki reaction has been greatly diversified, allowing for previously inaccessible non-ortho-substituted aromaticacids to undergo this transformation. The procedure also benefits from low catalyst loadings and the absence of stoichiometric transition metal additives.
Cascade Synthesis of 3-Alkylidene Dihydrobenzofuran Derivatives via Rhodium(III)-Catalyzed Redox-Neutral C–H Functionalization/Cyclization
作者:Zhi Zhou、Guixia Liu、Yan Chen、Xiyan Lu
DOI:10.1021/acs.orglett.5b03060
日期:2015.12.4
An efficient rhodium(III)-catalyzed coupling reaction of N-phenoxyacetamides with propargyl carbonates to yield 3-alkylidene dihydrobenzofuran derivatives via C–H functionalization/cascade cyclization has been developed. This transformation represents a redox-neutral process and features the formation of three new bonds under mild conditions.
Generation of Reactive Low-Valent Titanium Species Using Μetal−Αrenes as Efficient Organic Reductants for TiCl<sub>3</sub>: Applications to Organic Synthesis
for TiCl(3) has resulted in an efficient method for the generation of highly reactive low-valent titanium (LVT) reagents. The activated titanium species could be prepared by refluxing a mixture of substoichiometric amounts of arenes, TiCl(3), and Li/Mg in THF or DME. Among the LVT reagents screened, TiCl(3)--Li--naphthalene--THF (reagent I) was the best for coupling of carbonyls to olefins. The reagent
Wittig rearrangement and can be trapped with electrophiles. Their reactions with carboxylic esters afford the corresponding 2-aryl-3-hydroxy-2,3-dihydrobenzo[b]furans as a mixture of diastereoisomers. Subsequent acid-catalyzed or mediated dehydration gives moderate to good overall yield of a variety of 2-aryl-3-substituted benzo[b]furans.
用3当量的t -BuLi处理苄基2-卤代苯基醚会同时导致锂卤交换和在苄基亚甲基上的锂化。这些二价阴离子不进行维蒂希重排,并且可以被亲电试剂捕获。它们与羧酸酯的反应提供相应的2-芳基-3-羟基-2,3-二氢苯并[ b ]呋喃,为非对映异构体的混合物。随后的酸催化或介导的脱水使各种2-芳基-3-取代的苯并[ b ]呋喃具有中等至良好的总收率。