Mahiuddin Baidya

Copper-Catalyzed 8-Amido Chelation-Induced Remote C-H Amination of Quinolines.

A copper-catalyzed 8-amide chelation-induced remote C-H amination of quinolines has been developed. This direct amination with readily available azodicarboxylates proceeded with perfect C5-regioselectivity offering amino-substituted 8-aminoquinolines, important bioactive molecular scaffolds, in very high yields (up to 96%). A single-electron transfer (SET)-mediated mechanism with kH /kD =1.1 was proposed after trapping of the radical intermediate.

Copper-mediated etherification of arenes with alkoxysilanes directed by an (2-aminophenyl)pyrazole group

An efficient copper-mediated etherification of inert C–H bonds of (hetero)arenes with reagent-amounts of alkoxysilanes and alkanols has been developed using (2-aminophenyl)pyrazole (2-APP) as a removable directing group. The reaction is scalable, rapidly proceeds under an open atmosphere, and tolerates diverse functional groups to provide alkyl aryl ethers in high yields (up to 87%). As an application, the formal synthesis of anti-emetic drug metoclopramide is accomplished.

Ru(II)-Catalyzed Oxidative Heck-Type Olefination of Aromatic Carboxylic Acids with Styrenes through Carboxylate-Assisted C–H Bond Activation

A straightforward synthesis of 2-styrylbenzoic acids from aryl carboxylic acids is disclosed through a carboxylate-assisted coupling under Ru(II) catalysis. This protocol is simple and exhibits broad scope with high tolerance of common organic functional groups, providing good to excellent yields of diverse olefinated products. The efficacy of this protocol has been showcased through sequential syntheses of isochromanone, isocoumarin, and formal synthesis of anacardic acid derivative in good yields.

Radical Cascade Reaction of Aryl Alkynoates at Room Temperature: Synthesis of Fully Substituted α,β-Unsaturated Acids with Chalcogen Functionality

A radical-based cascade reaction has been devised for oxidative difunctionalization of aryl alkynoates at room temperature to access stereodefined fully substituted α,β-unsaturated acids bearing a chalcogen functionality in high yields (up to 95%). The protocol is operationally simple, metal-free, scalable, and suppresses the usual CO2 exclusion phenomenon. The utility of this method was showcased in the synthesis of vinyl halides, vinyl selenides, and 3,3-disubstituted indanones.

Platinum(II)-Catalyzed Novel Synthesis of 3,4-Fused Furans

Abstract A novel synthesis of 3,4-fused furans (both tricyclic and bicyclic) through platinum-catalyzed cyclization of 3-(2-formylcycloalkenyl)-acrylic amides 2 in methanol is described (up to 90% yield). Tricyclic 3,4-fused dihydrofuran derivatives were also obtained via reductive cyclization of 2. The substrates 2 were obtained from β- bromovinyl aldehydes by a Pd-catalyzed Heck reaction. GRAPHICAL ABSTRACT

Synthesis of Chiral 1,2-Oxazinanes and Isoxazolidines via Nitroso Aldol Reaction of Distal Dialdehydes

The first catalytic enantioselective nitroso aldol reaction of distal dialdehydes is reported. The reaction is catalyzed by simple l-proline at room temperature and subsequent reduction delivered biologically potent and synthetically versatile N-O bond containing five- and six-membered heterocycles, 1,2-oxazinanes, and isoxazolidines in high yields and excellent enantioselectivities (up to >99% ee). The method was further exploited to prepare chiral 3-hydroxypiperidines and -pyrrolidines that are otherwise difficult to access.

Divergent Reactivity of gem-Difluoro-enolates toward Nitrogen Electrophiles: Unorthodox Nitroso Aldol Reaction for Rapid Synthesis of α-Ketoamides

An amination reaction of in situ generated gem-difluoro-enolates has been explored with electrophilic nitrogen sources. While their exposure to azodicarboxylates smoothly produced fluorinated α-amino ketones, reaction with nitrosoarenes (nitroso aldol reaction) furnished α-ketoamides in very high yields (up to 94%). The reaction is very fast (typically completed within 5 min) and scalable and tolerates various sensitive functional groups. Synthetic utility of this process was highlighted through the production of diverse nitrogen heterocycles and an orexin receptor antagonist.

Directed C–H Bond Functionalization: A Unified Approach to Formal Syntheses of Amorfrutin A, Cajaninstilbene Acid, Hydrangenol, and Macrophyllol

Formal syntheses of natural products amorfrutin A, cajaninstilbene acid, hydrangenol, and macrophyllol have been accomplished on the basis of successive C-H bond functionalization of ready-stock benzoic acids. This concise strategy involves transition-metal-catalyzed directed C-H olefination, C-H hydroxylation, and acid-mediated C-H prenylation as key steps.

A Cross‐Dehydrogenative Annulation Strategy towards Synthesis of Polyfluorinated Phenanthridinones with Copper

The first cross-dehydrogenative annulation of (hetero)aromatic amides with polyfluoro(hetero)arenes is presented. This operationally simple oxidative annulation process is mediated by inexpensive copper salt, accommodates a wide range of substrates with exquisite chemo- and regioselectivity profile, and produces demanding polyfluorinated phenanthridinones in high yields (up to 92u2009%). Using alkenyl amides under identical conditions, the synthesis of polyfluorinated 2-quinolones has also been accomplished. Given the importance of fluorinated heterocycles in the pharmaceutical industry and drug discovery, this work is highly significant.