Iron-Promoted Difunctionalization of Alkenes by Phenylselenylation/1,2-Aryl Migration

Decennary Update on Oxidative-Rearrangement Involving 1,2-Aryl C-C Migration Around Alkenes: Synthetic and Mechanistic Insights

In recent years, numerous methodologies on oxidative rearrangements of alkenes have been investigated, that produce multipurpose synthons and heterocyclic scaffolds of potential applications. The present review focused on recently established methodologies for oxidative transformation via 1,2-aryl migration in alkenes (2013-2023). Special emphasis has been placed on mechanistic pathways to understand the reactivity pattern of different substrates, challenges to enhance selectivity, the key role of different reagents, and effect of different substituents, and how they affect the rearrangement process. Moreover, synthetic limitations and future direction also have been discussed. We believe, this review offers new synthetic and mechanistic insight to develop elegant precursors and approaches to explore the utilization of alkene-based compounds for natural product synthesis and functional materials.

Rhodium(III)-Catalyzed Oxidative 1,3-Aryl Migration of α-Aryl Allylic Alcohols

A Rh(III)-catalyzed oxidative 1,3-aryl migration of α-arylallylic alcohols via Csp2-Csp3 σ bond activation has been developed. This method provides an efficient strategy to allow for allylic alcohol-based skeleton rearrangement, in which various secondary and tertiary α-arylallylic alcohols are rapidly converted to β-aryl-α, β-unsaturated ketones and aldehydes.

Synthesis of Chalcogenylchromenes through Cyclization of Propargylic Aryl Ethers

We describe here for the first time the synthesis of 2-(chalcogenyl)-3H-benzo[f]chromenes and the new 3-(phenylselanyl)-2H-chromenes by the radical or electrophilic cyclization of propargylic aryl ethers in the presence of diorganyl diselenides or ditellurides using Oxone as a green oxidant and acetonitrile as solvent in a sealed tube at 100 °C. In this study, thirty-one chalcogenylchromenes with a broad substrate scope were prepared in moderate to excellent yields (50-98%), including compounds derived from natural products.

Synthesis of benzo[b]chalcogenophenes fused to selenophenes via intramolecular electrophilic cyclization of 1,3-diynes

We describe herein an alternative and transition-metal-free procedure for the access of benzo[b]chalcogenophenes fused to selenophenes via intramolecular cyclization of 1,3-diynes. This efficient protocol involves a double cyclization of 1,3-diynyl chalcogen derivatives promoted by the electrophilic species of organoselenium generated in situ by the oxidative cleavage of the Se-Se bond of dibutyl diselenide using Oxone® in acetonitrile as solvent in an open-flask at 80 °C. In this study, 15 selenophenes with broad substrate scope were prepared in moderate to excellent yields (55-98%) with short reaction times (0.5-3.0 h).

Chlorocyclization/cycloreversion of allylic alcohols to vinyl chlorides

Unprecedented chlorination of allylic alcohols: a simple mix-and-go procedure for the cyclization/cycloreversion of secondary and tertiary allylic alcohols with chloronium ions under mild conditions and practical access to remote carbonyl vinyl chlorides.

K2S2O8 promoted dehydrative cross-coupling between α,α-disubstituted allylic alcohols and thiophenols/thiols

K₂S₂O₈ promoted dehydrative cross-coupling between α,α-disubstituted allylic alcohols and thiophenols/thiols is demonstrated for the first time, leading to a wide range of allyl sulfides in good to high yields.

Recent Advances in the Synthesis of Selenophenes and Their Derivatives

The selenophene derivatives are an important class of selenium-based heterocyclics. These compounds play an important role in prospecting new drugs, as well as in the development of new light-emitting materials. During the last years, several methods have been emerging to access the selenophene scaffold, employing a diversity of cyclization-based synthetic strategies, involving specific reaction partners and particularities. This review presents a comprehensive discussion on the recent advances in the synthesis of selenophene-based compounds, starting from different precursors, highlighting the main differences, the advantages, and limitations among them.

Recent Advances on C-Se Bond-forming Reactions at Low and Room Temperature

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Over the last decades, many methods have been reported for the synthesis of selenium- heterocyclic scaffolds because of their interesting reactivities and applications in the medicinal as well as in the material chemistry. This review describes the recent numerous useful methodologies on C-Se bond formation reactions which were basically carried out at low and room temperature.

FeCl3-Catalyzed Regio-Divergent Carbosulfenylation of Unactivated Alkenes: Construction of a Medium-Sized Ring

A FeCl₃-catalyzed regio-divergent carbosulfenylation of unactivated alkenes with electrophilic N-sulfenophthalimides has been developed. This protocol provides a straightforward and efficient access to various medium-sized rings, especially strained 7- and 8-membered carborings with a sulfur atom attached. The endo/exo selectivity in the reaction depends on the atom number of the chain between arene and alkene. Broad substrate scope, high yields, and gram-scale synthesis exemplified the utility and practicability of this protocol. In addition, this methodology can be extended to the carboselenylation of isolated alkenes.

TEMPO promoted direct multi-functionalization of terminal alkynes with 2-oxindoles/benzofuran-2(3H)-one

Highly selective and catalyst-free tandem multi-functionalization of terminal alkynes was developed with 2-oxindoles and benzo-furan-2(3H)-one using TEMPO both as a radical promoter and a trapping reagent. This work expands the scope of the radical-cascade addition/trapping process of alkynes for the effective construction of various β-oxyl carbonyls in moderate to good yields.