Sadiya Raja

Ortho‐Quinone Methides as Reactive Intermediates in Asymmetric Brønsted Acid Catalyzed Cycloadditions with Unactivated Alkenes by Exclusive Activation of the Electrophile

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.

Combining Rhodium and Photoredox Catalysis for CH Functionalizations of Arenes: Oxidative Heck Reactions with Visible Light

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.

Asymmetric Brønsted acid-catalyzed nazarov cyclization of acyclic α-alkoxy dienones.

A Brønsted acid-catalyzed asymmetric Nazarov cyclization of acyclic α-alkoxy dienones has been developed. The reaction offers access to chiral cyclopentenones in a highly enantioselective manner. The reaction is complementary to our previously reported Brønsted acid-catalyzed electrocyclization reactions, which provided differently substituted optically active cyclopentenones with a fused tetrahydropyrane ring in good yields and with excellent enantioselectivities.

Experimental and Computational Study of the Catalytic Asymmetric 4π-Electrocyclization of N-Heterocycles†

The first asymmetric metal-catalyzed Nazarov cyclization of N-heterocycles has been developed. The use of a chiral catalyst allows the enantioselective electrocyclization of N-heterocycles under mild conditions and the corresponding products are obtained in good yields with excellent enantio- and diastereoselectivity. The reaction mechanism and the absolute configuration of the obtained products are explained by means of computational studies.

Asymmetric Brønsted acid-catalyzed aza-Diels–Alder reaction of cyclic C-acylimines with cyclopentadiene

Summary A new chiral Brønsted acid-catalyzed aza-Diels–Alder reaction of cyclic C-acylimines with cyclopentadiene has been developed. The reaction provides optically active aza-tetracycles in good yields with high diastereo- and enantioselectivities under mild reaction conditions.

Addition and Correction to Complete Field Guide to Asymmetric BINOL-Phosphate Derived Brønsted Acid and Metal Catalysis: History and Classification by Mode of Activation; Brønsted Acidity, Hydrogen Bonding, Ion Pairing, and Metal Phosphates

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

(1R,2S)-Methyl 1-(4-chloro­phen­yl)-3-oxo-1,2,3,4-tetra­hydro­cyclo­penta­[b]indole-2-carboxyl­ate 0.2-hydrate

The title compound, C19H14ClNO3·0.2H2O, crystallizes with five molecules and a disordered water molecule in the asymmetric unit. Four of the five molecules form hydrogen-bonded dimers via N—H⋯O hydrogen bonds towards another symmetry-independent molecule, whereas the fifth molecule forms a hydrogen-bonded dimer with its symmetry equivalent, also via N—H⋯O hydrogen bonds. The dihedral angle between the planes of the fused benzene ring and the five-membered ring to which it is attached is 79.45 (13), 49.00 (15), 72.49 (16), 81.91 (18) and 76.38 (16)° for the five molecules in the asymmetric unit.