Mannich Reactions of Carbohydrate Derivatives with Ketones To Afford Polyoxy-Functionalized Piperidines
作者:Lingaiah Maram、Fujie Tanaka
DOI:10.1021/acs.orglett.9b00105
日期:2019.2.15
Mannich reactions of carbohydrate derivatives with ketones that afford polyoxy-functionalized piperidines are reported. Ketone nucleophiles (enamines/enolates) were generated in the presence of the amines used for the formation of the iminium ions of sugar derivatives with or without an additive. Conditions to preferentially generate piperidine derivatives rather than tetrahydrofurans were identified
straightforward approach involves in situ formation and photoinduced activation of N‐chloroamines to give aminium radicals that enable efficient alkene aminochlorination. Owing to the ambiphilic nature of the β‐chloroamines produced, conversion into tetra‐alkyl aziridinium ions was possible, thus enabling diamination by regioselectivering‐opening with primary or secondary amines. This strategy streamlines
aerobic oxidative cyclization of β,γ-unsaturated hydrazones for the preparation of pyrazole derivatives has been developed. The hydrazonyl radical promoted the cyclization, along with a concomitant C═Cbondcleavage of β,γ-unsaturated hydrazones. This process has been verified via several control experiments, including a radical-trapping study, an 18O-labeling method, and the identification of the possible
Directed Markovnikov hydroarylation and hydroalkenylation of alkenes under nickel catalysis
作者:Zi-Qi Li、Omar Apolinar、Ruohan Deng、Keary M. Engle
DOI:10.1039/d1sc03121j
日期:——
Native Lewis basic functional groups enable the nickel-catalyzed Markovnikov-selective hydroarylation and hydroalkenylation of unactivated alkenes with organoboron reagents.
highly efficient Pd/Xiang-Phos catalyzedenantioselective carboetherification of alkenyl oximes with either aryl or alkenyl halides, delivering various chiral 3,5-disubstituted and 3,5,5-trisubstituted isoxazolines in good yields with up to 97 % ee. The sterically bulky and electron-rich (S,Rs)-NMe-X2 ligand is responsible for the excellent reactivities and enantioselectivities. The salient features of this