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A protocol involving intramolecular formal [4+2]‐cycloaddition of in situ generated o‐aza‐quinone methide for the facile synthesis of 1,4‐heterocycle‐fused quinoline motifs is demonstrated. The cascade involved tandem C−O, C−C, and C−N bond formation and also exhibited excellent functional group tolerance. Enantiomerically enriched 1,4‐oxazepino quinolines were synthesized using alkynols derived from L‐amino acids. The sulfoxide embedded quinolines were transformed to pentacyclic 1,4‐thiepino tethered indeno‐quinoline scaffolds via Pummerer cyclization. [ABSTRACT FROM AUTHOR]

Enallenylamides have been utilized for the synthesis of heterobicycle[4.2.0]octane derivatives via Ir/hν promoted [2+2] cycloaddition reaction. The reaction specifically targets the distal double bond of the allene moiety, and results in the exclusive formation of the trans product. The process is conducted at room temperature and under an inert atmosphere. An extensive study on the substituent propensities during the cycloaddition step revealed variable effects. Electron‐withdrawing groups conjugated with the double bond participating in the cycloaddition either hindered the process or reduced its yield. Conversely, electron‐donating substituents enhanced the efficiency, resulting in product yields ranging from 60% to 88%. Our study also demonstrated the influence of protecting groups on the reaction pathway. [ABSTRACT FROM AUTHOR]

Dearomatization reactions are among the most efficient chemical processes, combining atom economy, stereospecificity and the ability to generate molecular complexity in a single step. Dearomative vinylation reactions provide a synthetic connection between readily available, simple aromatic starting materials and more unsaturated alkynes. The last decade has witnessed a steady increase in the development of transition metal‐catalyzed dearomative vinylation methods of electron rich aromatic compounds with alkynes, providing new synthetic approaches to high‐value building blocks and natural products. This review aims to serve as a comprehensive reference for work in transition metal‐catalyzed dearomative vinylation reactions of electron rich aromatic compounds with alkynes. [ABSTRACT FROM AUTHOR]

A Lewis acid catalyzed carbofunctionalization of styrenes with diacyl peroxides and nucleophiles, including amines, indoles, trimethoxybenzenes, and carboxylic acid, has been accomplished. A wide range of primary, secondary, and tertiary alkyl diacyl peroxides generated from inexpensive aliphatic acids serve as both simple alkylating reagents and internal oxidants for the synthesis of value‐added amines, indoles, 1,1‐diarylalkanes, and esters in moderate to good yields. This protocol features site selectivity, broad substrate scope, and mild reaction conditions. [ABSTRACT FROM AUTHOR]

One‐pot synthesis of 2,3‐disubstituted 4‐aminoquinolines is developed through a three‐component reaction of 2‐azidobenzaldehydes, α‐fluoro‐β‐ketoesters and amines involving cascade Mannich, aza‐Wittig and dehydrofluorinative aromatization. The method is applicable to other functionalized quinolines. It is a pot, atom and step economy (PASE) synthesis of biologically interesting 4‐aminoquinolines relevant to hydroxychloroquine and chloroquine. [ABSTRACT FROM AUTHOR]

An organocatalytic enantioselective synthesis of δ‐lactone‐fused 4‐chromanones was demonstrated using 1‐(2‐hydroxyaryl)‐1,3‐butanedione and α,β‐unsaturated aldehydes in the presence of the Jørgensen‐Hayashi catalyst. The reaction proceeded through a Michael addition/cycloketalization/hemiacetalization sequence, and the resulting hemiacetals were oxidized into the corresponding lactone derivatives in a one‐pot manner. The desired fused O,O‐ketal tricyclic lactone motifs containing three contiguous chiral centers were obtained in excellent chemical yields (up to 97%) and with high stereoselectivities (up to >20:1 dr and up to 95% ee). [ABSTRACT FROM AUTHOR]

This work first discloses a new strategy for amine activation to give reactive amine anion by in situ generated iminium cation‐amine anion pair through decomposition of sterically hindered aminals. Utilizing this strategy, a highly regio‐ and chemoselective cyclocarboamination of ortho‐formyl phenylacetylenes with secondary amines has been realized under metal‐free mild reaction conditions. The cyclocarboamination with notably tunable product profiles depends on the separation and purification procedure, a diverse range of 1, 3‐diamino‐1H‐indenes (essentially reactive enamines) and 3‐amino‐1‐indanones were obtained, respectively. Moreover, using iodine as an electrophile to couple with various ortho‐formyl phenylacetylenes and secondary amines, a series of 3‐amino‐2‐iodo‐1‐indanones were efficiently achieved with four bonds (C=O, C−C, C−N and C−I) formation in an one‐pot three‐component reaction. These results demonstrated an unprecedented methodology for the construction of highly functionalized 1H‐indene and 1‐indanone compounds. [ABSTRACT FROM AUTHOR]

An efficient copper‐catalyzed cyclization of o‐azidobenzaldehyde and nitro‐olefins was developed. This reaction proceeds under solvent‐free conditions and displays broad functional group compatibility and affords 3‐nitroquinolines in good to excellent yields. The synthetic utility of this strategy is illustrated by the concise construction of quindolines in only three steps, which renders the reaction more practical. [ABSTRACT FROM AUTHOR]

Abstract: A highly diastereoselective cascade annulation process of p‐quinols with β′‐acetoxy allenoate catalyzed by phosphine has been developed, which comes up with highly functionalized multiple ring‐fused hexahydroindeno furan derivatives in synthetically useful yields and creates three consecutive stereogenic carbon centers only in a one‐step manner. The salient features of this phosphine‐catalyzed cyclization include the use of p‐quinol's three active sites in this cascade reaction, wide substrate scope, excellent functional group tolerance, mild reaction conditions, asymmetric version, good yields, ease of scale‐up to gram scale, and further transformations. [ABSTRACT FROM AUTHOR]

Abstract: A gold(I)/Brønsted acid‐catalyzed cyclization of 2‐azidobenzaldehydes with 3‐aza‐1,6‐enynes has been developed for the synthesis of tetrahydrobenzo[b][1,8]naphthyridine derivatives. This protocol enabled the modular synthesis of tetracyclic heterocycles in one operation with water and nitrogen gas as the byproducts. [ABSTRACT FROM AUTHOR]