The preparation of a series of sterically constrained phenyleneethynylenes is described. Restricting the interannular rotation significantly narrows the lowest energy absorption and increases its extinction coefficient in the UV/VIS spectrum. (C) 1997 Elsevier Science Ltd.
We have developed highly enantioselective synthesis of functionalized helically chiral molecules via a Rh-catalyzed [2 + 2 + 2] cycloaddition and synthesis of ladder-type molecules via an unprecedented Rh-catalyzed formal [2 + 1 + 2 + 1] cycloaddition involving C−C triple bond cleavage.
990. Complexes of acetylenes with platinum(II). Part II. Hydroxy- and methoxy-alkylacetylenes
作者:J. Chatt、R. G. Guy、L. A. Duncanson、D. T. Thompson
DOI:10.1039/jr9630005170
日期:——
Exploring the Potential of Diarylacetylenediols as Hydrogen Bonding Catalysts
作者:Yunus E. Türkmen、Viresh H. Rawal
DOI:10.1021/jo400926n
日期:2013.9.6
In the course of a search for new classes of hydrogen bonding catalysts, we have examined diarylacetylenediols as potential catalysts for the Diels-Alder reaction. General and efficient methods have been developed for the preparation of these diols. Their structures were systematically modified, and increased activity was observed for those possessing an electron-withdrawing group on the aryl groups. The electron-deficient diarylacetylenediol catalysts, while more active, undergo spontaneous cyclization to the corresponding benzo[b]furans. A mechanism is postulated to explain this facile transformation. Computational studies performed on 2-ethynylphenol help to explain the effect of the alkyne on the conformation and hydrogen bond donating ability of the adjacent OH group. Finally, the crystal structure of one of the diols is reported, and it displays an intricate network of intermolecular hydrogen bonds.
Organoboron Compounds. XI. Isomerization of 2,2'-Tolandiboronic Acid<sup>1</sup>
作者:Robert L. Letsinger、John R. Nazy
DOI:10.1021/ja01521a024
日期:1959.6
VITAMIN C, VITAMIN K, A POLYPHENOL, AND COMBINATIONS THEREOF FOR WOUND HEALING