attached to 2-(hydroxymethyl)pyridinooxazoline and bis[4-(hydroxymethyl)oxazoline] compounds. The new ligands obtained were assessed in palladium-catalyzedallylicalkylations. The first type of ligands exhibited enantioselectivity similar to that of a benzoyl ester derivative, whereas the latter type of ligands afforded products with higher selectivity than the analogous benzoyl ester. The activity of the
Bisdiamidophosphite with a bisoxazoline moiety in palladium-catalyzed enantioselective allylation
作者:K. N. Gavrilov、S. V. Zheglov、V. K. Gavrilov、I. D. Firsin、M. G. Maksimova
DOI:10.1007/s11172-019-2564-6
日期:2019.7
A bisdiamidophosphite ligand with stereogenic phosphorus atoms as a part of 1,3,2-diaza-phospholidine rings and a bisoxazoline backbone was synthesized and studied in the Pd-catalyzed asymmetric allylic substitution. The use of this ligand provided up to 93% ee in the alkylation of (E)-1,3-diphenylallyl acetate with dimethyl malonate and up to 77% ee in the amination with pyrrolidine at quantitative conversion of the starting substrate.
A New Copper<sup>II</sup>/Isopropylidene-2,2-bis(oxazoline) Catalyst and Its Stable Reactive Complex with Acryloyloxazolidinone in Enantioselective Reactions
ghost: The [TIPS‐box/Cu(OTf)2] complex (box = isopropylidene‐2,2‐bis(oxazoline)) is a catalyst of the Diels–Alder and the 1,3‐dipolar cycloaddition between acryloyl‐1,3‐oxazolidin‐2‐one with cyclopentadiene and diphenylnitrone with ee values of 75 and 85 %, respectively. The reacting complex (see figure) of the above reactions was, for the first time, isolated and its structure determined by X‐ray spectroscopy
The diastereo- and enantioselective cyclopropanation of furans was achieved in up to 91% ee using a new set of chiral bis(oxazoline) ligands that are able to use secondary binding sites to enhance selectivity. In contrast, with substrates such as styrene and N-Boc-pyrrole, with which no secondary interactions with the ligands can occur, only moderate selectivities (<50% ee) were achieved. (C) 2003 Elsevier Science Ltd. All rights reserved.
New Applications of Bis(oxazoline) Ligands in Catalysis: Asymmetric 1,2- and 1,4-Addition of ZnR<sub>2</sub> to Carbonyl Compounds
The enantioselective addition of ZnR(2) to aldehydes (1,2) and cyclic enones (1,4) was accomplished using bis(oxazolines) as chiral ligands. The requirement for hydroxymethylene side chains in the ligands strongly suggests that bimetallic catalysts are decisive for high enantiocontrol in these additions. [structure: see text]