Highly Selective Synthesis of (<i>E</i>)-3-Methyl-1-trialkylsilyl-3-en-1-ynes via <i>trans</i>-Selective Alkynylation Catalyzed by Cl<sub>2</sub>Pd(DPEphos) and Stereospecific Methylation with Methylzincs Catalyzed by Pd(<i><sup>t</sup></i>Bu<sub>3</sub>P)<sub>2</sub>
作者:Ji-cheng Shi、Xingzhong Zeng、Ei-ichi Negishi
DOI:10.1021/ol030017x
日期:2003.5.1
[reaction: see text] trans-Selective (>or=98%) monoalkynylation of 1,1-dibromo-1-alkenes and 1,1-dichloro-1-alkenes catalyzed by Cl(2)Pd(DPEphos) followed by stereospecific methylation with Me(2)Zn or MeZnX (X= Cl or Br) catalyzed by Pd((t)()Bu(3)P)(2) provides an efficient and stereoselective (>or=98%) route to 5, convertible to a wide variety of enynes and conjugated dienes. In the cases of 1,1-dibromo-1-alkenes
Synthesis of conjugated enediynes via palladium catalyzed cross-coupling reactions of potassium alkynyltrifluoroborates
作者:George W. Kabalka、Gang Dong、Bollu Venkataiah
DOI:10.1016/j.tetlet.2004.12.021
日期:2005.1
An efficient synthesis of cross-conjugated enediynes has been developed utilizing the palladium catalyzedcross-couplingreactions of 1,1-dibromo-1-alkenes with potassium alkynyltrifluoroborates under mild conditions.
Photophysics and peripheral ring size dependent aggregate emission of cross-conjugated enediynes: applications to white light emission and vapor sensing
作者:Anuja Singh、Avik Kumar Pati、Ashok Kumar Mishra
DOI:10.1039/c7cp08091c
日期:——
local nature of the dominant electronic transition. The optimized groundstate geometries of the dyes from partially to fully propeller shaped structures confirm the ring-size dependence of the aggregates. The LE and aggregate state emissions are judiciously exploited to generate single-component white light emission in binary solvent mixtures. The excited state photophysics are further applied toward
Synthesis and Photophysical Studies of Bis-enediynes as Tunable Fluorophores
作者:Gil Tae Hwang、Hyung Su Son、Ja Kang Ku、Byeang Hyean Kim
DOI:10.1021/ja0349148
日期:2003.9.1
We have synthesized a family of bis-enediynes by two complementary Pd/Cu-catalyzed Sonogashira cross-coupling methods. One is a modified Sonogashira reaction between the TMS-protected tetraalkyne 20 (or 21) and various aromatic bromides to afford bis-enediynes 22a-d and 23a-d bearing different peripheral aryl units. The other, the reaction of bifunctional 1,1-dibromo-1-alkenes with phenylacetylene, afforded a series of bis-enediynes 24-32 bearing various core aryl groups. These chemical modifications to the core and periphery of bis-enediynes induce dramatic changes in absorption and emission spectra. Bis-enediynes 22 and 23 show a large Stokes shift of about 50-110 nm when compared to the less-conjugated bis-enediynes 20 and 21. Absorptions and emissions of bis-enediynes 25, 27-29, and 31 were red-shifted relative to those of enediyne 35. Substantial increases in fluorescence quantum yields are observed as a result of extending the T-conjugation. The emission wavelength of bis-enediynes was tailored from indigo blue to reddish-orange, suggesting that the color of emission can be tunable by modification of the core and/or peripheral units.
Palladium-catalyzed trans-selective alkynylation–alkylation tandem process for the synthesis of (E)-3-alkyl-1-trialkylsilyl-3-alken-1-ynes
作者:Ei-ichi Negishi、Ji-cheng Shi、Xingzhong Zeng
DOI:10.1016/j.tet.2005.07.100
日期:2005.10
The Pd-catalyzed trans-selective monoalkynylation of 1,1-dihalo-l-alkenes with XZnC CSiMe3, where X is Br or Cl, can proceed generally in excellent yields in the presence of Pd(DPEphos)Cl-2 or Pd(dppf)Cl-2, and subsequent alkylation with methyl- and ethylzincs can proceed in excellent yields with >= 98% retention of configuration in the presence of Pd((BU3P)-B-t)(2) as a catalyst. (c) 2005 Elsevier Ltd. All rights reserved.