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Sadiya Raja

Bio: Sadiya Raja is an academic researcher from RWTH Aachen University. The author has contributed to research in topics: Catalysis & Enantioselective synthesis. The author has an hindex of 13, co-authored 21 publications receiving 1929 citations.

Papers
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Journal ArticleDOI
TL;DR: An efficient method for the highly enantioselective synthesis of chiral chromanes bearing multiple stereogenic centers was developed and a chiral BINOL-based N-triflylphosphoramide proved to be an effective catalyst for the in-situ generation of ortho-quinone methides.
Abstract: An efficient method for the highly enantioselective synthesis of chiral chromanes bearing multiple stereogenic centers was developed. A chiral BINOL-based N-triflylphosphoramide proved to be an effective catalyst for the in situ generation of ortho-quinone methides (o-QMs) and their subsequent cycloaddition reaction with unactivated alkenes provided chromanes with excellent diastereo- and enantioselectivity.

171 citations

Journal ArticleDOI
TL;DR: Small amounts (1 mol%) of a photoredox catalyst resulted in the efficient C-H functionalization of a broad range of substrates under mild conditions.
Abstract: Direct, oxidative metal-catalyzed C-H functionalizations of arenes are important in synthetic organic chemistry. Often, (over-)stoichoimetric amounts of organic or inorganic oxidants have to be used in these reactions. The combination of rhodium and photoredox catalysis with visible light allows the direct C-H olefination of arenes. Small amounts (1 mol%) of a photoredox catalyst resulted in the efficient C-H functionalization of a broad range of substrates under mild conditions.

142 citations

Journal ArticleDOI
TL;DR: The pKa values were measured and found to correlate directly with the catalytic properties of the acids: higher rate constants kI were observed for more acidic Brønsted acid catalysts (see plot; binol=1,1'-bi-2-naphthol).
Abstract: Stronger acid, higher speed: The pKa values of a range of binol-derived Bronsted acids of three different types were measured and found to correlate directly with the catalytic properties of the acids: higher rate constants kI were observed for more acidic Bronsted acid catalysts (see plot; binol=1,1'-bi-2-naphthol).

131 citations

Journal ArticleDOI
TL;DR: The proposed catalyst/substrate interaction shown in Figure 73 corresponds to the related sulfoxidation catalyzed by chiral phosphoric acid PA 5, and an alternative mechanism has been proposed, as discussed in the surrounding text.
Abstract: Figure 73: The proposed catalyst/substrate interaction shown in Figure 73 corresponds to the related sulfoxidation catalyzed by chiral phosphoric acid PA 5 (ref 133). Please note that this interaction will be different for PA 43. Figure 105 and surrounding text: The asymmetric reduction was achieved with 1 mol % (S)-PA 25 (ref ). Figure 176 and surrounding text: For the first example of the application of asymmetric counteranion directed catalysis with phosphoric acid salts as catalysts, see ref 29d. Figure 192: The proposed transition state corresponds to the spiroacetalization catalyzed by chiral phosphoric acid (S)-PA 25 (ref 373). Please note that this will be different for PA 43. Figure 196: The correct substrate used is TMSN3. Please note that an alternative mechanism has been proposed (ref 381), as discussed in the surrounding text. Figure 228: The correct structure of 427 is

130 citations


Cited by
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Journal ArticleDOI
TL;DR: This Perspective highlights the unique ability of photoredox catalysis to expedite the development of completely new reaction mechanisms, with particular emphasis placed on multicatalytic strategies that enable the construction of challenging carbon-carbon and carbon-heteroatom bonds.
Abstract: In recent years, photoredox catalysis has come to the forefront in organic chemistry as a powerful strategy for the activation of small molecules. In a general sense, these approaches rely on the ability of metal complexes and organic dyes to convert visible light into chemical energy by engaging in single-electron transfer with organic substrates, thereby generating reactive intermediates. In this Perspective, we highlight the unique ability of photoredox catalysis to expedite the development of completely new reaction mechanisms, with particular emphasis placed on multicatalytic strategies that enable the construction of challenging carbon–carbon and carbon–heteroatom bonds.

1,808 citations

Journal ArticleDOI
TL;DR: This Review summarizes dual-catalyst strategies that have been applied to synthetic photochemistry, and focuses upon the cooperative interactions of photocatalysts with redox mediators, Lewis and Brønsted acids, organocatalyst, enzymes, and transition metal complexes.
Abstract: The interaction between an electronically excited photocatalyst and an organic molecule can result in the genertion of a diverse array of reactive intermediates that can be manipulated in a variety of ways to result in synthetically useful bond constructions. This Review summarizes dual-catalyst strategies that have been applied to synthetic photochemistry. Mechanistically distinct modes of photocatalysis are discussed, including photoinduced electron transfer, hydrogen atom transfer, and energy transfer. We focus upon the cooperative interactions of photocatalysts with redox mediators, Lewis and Bronsted acids, organocatalysts, enzymes, and transition metal complexes.

1,744 citations

01 Feb 1995
TL;DR: In this paper, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
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

1,652 citations

Journal ArticleDOI
TL;DR: This review presents the current state of the art in this field and detail C-H activation transformations reported since 2011 that proceed either at or below ambient temperature, in the absence of strongly acidic or basic additives or without strong oxidants.
Abstract: Organic reactions that involve the direct functionalization of non-activated C–H bonds represent an attractive class of transformations which maximize atom- and step-economy, and simplify chemical synthesis. Due to the high stability of C–H bonds, these processes, however, have most often required harsh reaction conditions, which has drastically limited their use as tools for the synthesis of complex organic molecules. Following the increased understanding of mechanistic aspects of C–H activation gained over recent years, great strides have been taken to design and develop new protocols that proceed efficiently under mild conditions and duly benefit from improved functional group tolerance and selectivity. In this review, we present the current state of the art in this field and detail C–H activation transformations reported since 2011 that proceed either at or below ambient temperature, in the absence of strongly acidic or basic additives or without strong oxidants. Furthermore, by identifying and discussing the major strategies that have led to these improvements, we hope that this review will serve as a useful conceptual overview and inspire the next generation of mild C–H transformations.

1,373 citations