Iodine-Mediated Direct Generation of <i>o</i>
-Quinone Methides at Room Temperature: A Facile Protocol for the Synthesis of <i>ortho</i>
-Hydroxybenzyl Thioethers
作者:R. Sidick Basha、Chia-Wei Chen、Daggula Mallikarjuna Reddy、Chin-Fa Lee
DOI:10.1002/asia.201800233
日期:2018.9.4
An iodine‐mediated preparation of ortho‐quinonemethides (o‐QMs) from ortho‐hydroxybenzylalcohols by a C−O bond scission strategy is described. The in situ generated o‐QMs were then employed for C−S bond formation by thio‐Michael addition of thiols to provide the ortho‐hydroxybenzyl thioethers (o‐HBT) in moderate to excellent yields.
Using the [Ru(p-cymene)Cl-2](2) (1) complex, catalytic hydroboration of aldehydes and ketones with pinacolborane under neat and mild conditions is reported. At rt, chemoselective hydroboration of aldehydes over the ketones is also attained. Mechanistic studies confirmed the immediate formation of monohydride bridged dinuclear complex [(eta(6)-p-cymene)RuCl}(2)(mu-H-mu-Cl)] (1b) from the reaction of 1 with pinacolborane, which catalyzed the highly efficient hydroboration reactions. The catalytic cycle containing mononuclear Ru-H species and intramolecular 1,3-hydride transfer is postulated.