A. Meetsma

Bio: A. Meetsma is an academic researcher from University of Groningen. The author has contributed to research in topics: Enantioselective synthesis & Catalysis. The author has an hindex of 7, co-authored 24 publications receiving 399 citations. Previous affiliations of A. Meetsma include Indian Institute of Technology Madras.

Catalytic asymmetric conjugate addition/oxidative dearomatization towards multifunctional spirocyclic compounds.

Abstract: The convenient one-pot procedure includes conjugate addition of alkylmagnesium bromides to α,β-unsaturated esters and subsequent oxidative cyclization.

Highly Enantioselective Synthesis of 3‐Substituted Furanones by Palladium‐Catalyzed Kinetic Resolution of Unsymmetrical Allyl Acetates

Abstract: The Pd-catalyzed asymmetric allylic alkylation (AAA) holds a prominent position among the most versatile methods for C C bond formation that are widely applied in natural product synthesis. This transformation typically features broad functional group tolerance and excellent regioand enantioselectivity. In particular, Pd-catalyzed kinetic resolutions of symmetrical allylic substrates and dynamic kinetic transformations have been developed recently, which extends their potential in synthetic chemistry. However, Pd-catalyzed kinetic resolutions of unsymmetrical acyclic allylic substrates with high yield and enantioselectivity are rare. Furthermore, the enantioselective allylic alkylation of silyl enol ethers is still a challenging reaction. Graening and Hartwig reported a highly enantioselective alkylation of monosubstituted allylic substrates with silyl enol ethers catalyzed by an Ir complex. Although excellent results of allylic alkylations have been reported with enolates that are preformed or generated in situ, to the best of our knowledge, Pd-catalyzed AAAwith a nonstabilized silyl enol ether as nucleophile remains an elusive goal (Scheme 1). Herein, we present the Pd-catalyzed kinetic resolution of 1,3-disubstituted unsymmetrical allylic substrates with nonstabilized silyl enol ethers as nucleophiles, which provides a highly regioand enantioselective synthesis of 3-substituted g-butenolides. The g-butyrolactone skeleton is present in more than 13000 natural products, which have attracted considerable attention because of the range of important biological activities associated with this class of compounds. As part of our program to develop catalytic enantioselective methods to access optically active g-butenolides and lactones, we envisioned the possibility of using 2-trimethylsilyloxyfuran (TMSOF) as nucleophile in a Pd-catalyzed AAA reaction. Initially, we examined the allylic substitution of carbonate 1a by utilizing TMSOFas nucleophile and a chiral Pd catalyst based on Trost Ligand L1 (Table 1, entry 1). The 3-substituted product 3 and 5-substituted product 4 were obtained in a 2:1 ratio and in 36% ee for product 3 (Table 1, entry 1). Using a lower temperature (0 8C), the ee value only slightly increased (49% ee, Table 1, entry 2). With tert-butyl carbonate as the leaving group, the regioselectivity shifted in favor of the formation of the 5-substituted product (3/4= 1:2, Table 1,

A three-component reaction of phenol, aldehyde, and active methylene substrate under Lewis acid catalysis: Successful trapping of o-quinone methide to afford benzopyran systems

Abstract: A three-component condensation involving reactive phenols, aldehydes, and active methylene substrates is described under BF3.Et2O catalysis to afford benzopyranyl products in satisfactory yields.

High-pressure diels-alder reactions of 1-vinyl-2,2,6-trimethylcyclohexene catalyzed by chiral lewis-acids - an enantioselective route to a drimane sesquiterpene precursor

Abstract: The Diels Alder reaction of 1-vinyl-2,2,6-trimethylcyclohexene 4 and 3-((E)-3-(methoxycarbonyl)propenoyl)-1,3-oxazolidin-2-one 5 under high pressure, catalyzed by a chiral bis-imine copper(II) complex, yields a drimane sesquiterpene precursor in a highly regio- and diastereoselective manner with enantioselectivities up to 64%; nearly enantiomerically pure material is obtained by one simple crystallization.

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Catalytic Asymmetric Dearomatization Reactions

Abstract: This Review summarizes the development of catalytic asymmetric dearomatization (CADA) reactions. The CADA reactions discussed herein include oxidative dearomatization reactions, dearomatization by DielsAlder and related reactions, the alkylative dearomatization of electron-rich arenes, transition-metal-catalyzed dearomatization reactions, cascade sequences involving asymmetric dearomatization as the key step, and nucleophilic dearomatization reactions of pyridinium derivatives. Asymmetric dearomatization reactions with chiral auxiliaries and catalytic asymmetric reactions of dearomatized substrates are also briefly introduced. This Review intends to provide a concept for catalytic asymmetric dearomatization.

Development of a coordination chemistry-based approach for functional supramolecular structures.

Abstract: The weak-link approach (WLA) to supramolecular assemblies allows for the design of multimetallic two- and three-dimensional arrays, host-guest architectures, sensors, catalysts, switches, and signal amplification devices. This Account describes the course of our investigations in this area beginning with the development of a chemical tool kit of building blocks consisting of multiple metals and ligands. These building blocks can be rationally mixed and matched to provide structures with a wide range of properties that have been used to develop functional supramolecular architectures, including chemical sensors and allosteric catalysts.

Phosphoramidites: Privileged Ligands in Asymmetric Catalysis

Abstract: Asymmetric catalysis with transition-metal complexes is the basis for a vast array of stereoselective transformations and has changed the face of modern synthetic chemistry. Key to this success has been the design of chiral ligands to control the regio-, diastereo-, and enantioselectivity. Phosphoramidites have emerged as a highly versatile and readily accessible class of chiral ligands. Their modular structure enables the formation of ligand libraries and easy fine-tuning for a specific catalytic reaction. Phosphoramidites frequently show exceptional levels of stereocontrol, and their monodentate nature is essential in combinatorial catalysis, where a ligand-mixture approach is used. In this Review, recent developments in asymmetric catalysis with phosphoramidites used as ligands are discussed, with a focus on the formation of carbon-carbon and carbon-heteroatom bonds.