AbstractThe N‐heterocyclic carbene palladium complex (SIPr)Pd(cinnamyl)Cl [SIPr=N,N′‐bis(2,4,6‐trimethylphenyl)‐4,5‐dihydroimidazol‐2‐ylidene) promotes regio‐ and stereospecific dimerization of a variety of arylalkynes to give (E)‐1,3‐enynes in good to excellent yields. An efficient and practical procedure for their synthesis was developed using a biphasic aqueous alkali/heptane system. Optical and electronic properties of (E)‐1,3‐enynes are highly tunable. Depending on the nature of the substituents, HOMO energies vary in the range 5.3–6.0 eV. (E)‐1,3‐Enynes can exhibit intense photoluminescence in the spectral region 350–500 nm.magnified image
AbstractThe N‐heterocyclic carbene palladium complex (SIPr)Pd(cinnamyl)Cl [SIPr=N,N′‐bis(2,4,6‐trimethylphenyl)‐4,5‐dihydroimidazol‐2‐ylidene) promotes regio‐ and stereospecific dimerization of a variety of arylalkynes to give (E)‐1,3‐enynes in good to excellent yields. An efficient and practical procedure for their synthesis was developed using a biphasic aqueous alkali/heptane system. Optical and electronic properties of (E)‐1,3‐enynes are highly tunable. Depending on the nature of the substituents, HOMO energies vary in the range 5.3–6.0 eV. (E)‐1,3‐Enynes can exhibit intense photoluminescence in the spectral region 350–500 nm.magnified image
Esters as Radical Acceptors: β‐NHC‐Borylalkenyl Radicals Induce Lactonization by C−C Bond Formation/Cleavage on Esters
作者:Masaki Shimoi、Katsuhiro Maeda、Steven J. Geib、Dennis P. Curran、Tsuyoshi Taniguchi
DOI:10.1002/anie.201902001
日期:2019.5.6
Substituted propargyl acetates are converted into 4‐boryl‐2(5H)‐furanones upon thermolysis in the presence of an N‐heterocyclic carbene borane (NHC‐borane) and di‐tert‐butyl peroxide. The acetyl methyl group is lost during the reaction as methane. Evidence suggests that the reaction proceeds by a sequence of radical events including: 1) addition of an NHC‐boryl radical to the triple bond; 2) cyclization