Electron-Withdrawing Trifluoromethyl Groups in Combination with Hydrogen Bonds in Polyols: Brønsted Acids, Hydrogen-Bond Catalysts, and Anion Receptors
作者:Alireza Shokri、Xue-Bin Wang、Steven R. Kass
DOI:10.1021/ja4036384
日期:2013.6.26
Electron-withdrawing trifluoromethyl groups were characterized in combination with hydrogen bond interactions in three polyols (i.e., CF3CH(OH)CH2CH(OH)CF3, 1; (CF3)(2)C(OH)C-(OH)(CF3)(2), 2; ((CF3)(2)C(OH)CH2)(2)CHOH, 3) by pK(a) measurements in DMSO and H2O, negative ion photoelectron spectroscopy and binding constant determinations with Cl-. Their catalytic behavior in several reactions were also examined and compared to a Bronsted acid (HOAc) and a commonly employed thiourea ((3,5-(CF3)(2)C6H3NH)(2)CS). The combination of inductive stabilization and hydrogen bonds was found to afford potent acids which are effective catalysts. It also appears that hydrogen bonds can transmit the inductive effect over distance even in an aqueous environment, and this has far reaching implications.
Alternating Terpolymers through Cyclopolymerization and Subsequent Orthogonal Functionalization
作者:Philipp Gerdt、Armido Studer
DOI:10.1002/anie.202206964
日期:2022.9.26
The alternating radical copolymerization of divinylmonomer A and hex-5-enyl vinyl ether (HVE) using reversible addition–fragmentation chain transfer (RAFT) is reported. The obtained cyclopolymer B can chemically be further modified by three orthogonal functionalization reactions i.e. thiol-ene click reaction, amidation and transesterification or acylation to provide access to various alternating ABC-type