55190-55-1Relevant academic research and scientific papers
Ruthenium-Catalyzed Direct Asymmetric Reductive Amination of Diaryl and Sterically Hindered Ketones with Ammonium Salts and H2
Hu, Le' an,Zhang, Yao,Zhang, Qing-Wen,Yin, Qin,Zhang, Xumu
supporting information, p. 5321 - 5325 (2020/02/28)
A Ru-catalyzed direct asymmetric reductive amination of ortho-OH-substituted diaryl and sterically hindered ketones with ammonium salts is reported. This method represents a straightforward route toward the synthesis of synthetically useful chiral primary diarylmethylamines and sterically hindered benzylamines (up to 97 % yield, 93–>99 % ee). Elaborations of the chiral amine products into bioactive compounds and a chiral ligand were demonstrated through manipulation of the removable and convertible -OH group.
Chemistry of photogenerated α-phenyl-substituted o-, m-, and p-quinone methides from phenol derivatives in aqueous solution
Diao, Li,Wan, Peter
, p. 105 - 118 (2008/09/18)
The enhanced photochemical reactivity of o-substituted phenols in its propensity to give o-quinone methide (o-QM) intermediates via excited state intramolecular proton transfer (ESIPT) was uncovered by Keith Yates as part of his now classic studies of photohydration of aromatic alkenes, alkynes, and related compounds. Photogeneration of QMs and the study of their chemistry along with potential biological applications are the focus of many groups. In this work, photochemical precursors to o-, m-, and p-QMs based on substituted phenols (hydroxybenzyl alcohols) and related compounds have been studied in aqueous solution as a function of pH and water content. The focus will be on QMs that are stabilized by an a-phenyl substituent, which enhances quantum yields for their formation, with the resulting QMs having longer lifetimes and easier to detect. Noteworthy is that all QM isomers can. be photogenerated with the o and m isomers being the most efficient, consistent with the Zimmerman "ortho-meta" effect. m-QMs have formal non-Kekule structures, and although they can be routinely photogenerated, are found to be most reactive. One m-QM was found, to undergo a photocondensation reaction at high pH giving rise to m-substituted oligomers. The mechanism, of QM formation in aqueous solution is believed to involve singlet excited phenols that undergo adiabatic deprotonation to give the corresponding photoexcited phenolate ion, which subsequently expels the hydroxide ion (photodehydroxylation). A pathway involving direct loss of water for the o-isomers is also possible in organic solvents.
