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Photoredox catalysis is employed to generate highly reactive acylnitroso species from hydroxamic acid derivatives. The conditions are shown to be comparable to a previously developed transition metal aerobic oxidation and are amenable to a range of transformations including Diels–Alder and ene reactions. This unique application of such an approach gives access to temporal and spatial control in nitroso chemistry. [ABSTRACT FROM AUTHOR]

Abstract: 4-Hydroxycyclopentenones represent a privileged scaffold in chemical synthesis. A dysprosium(III) trifluoromethanesulfonate catalyzed rearrangement of furylcarbinols to 4-hydroxycyclopentenones via a 4π electrocyclization has been developed. The catalytic Piancatelli rearrangement affords a single trans-diastereomer from both aryl and alkyl substituted furylcarbinols. [Copyright &y& Elsevier]

This account describes the discovery and development of mild and efficient protocols for the generation of highly reactive nitroso compounds to allow their subsequent use in previously inaccessible or challenging chemistries. 1 Introduction 2 Formation of Nitrosocarbonyl Compounds 3 The Nitrosocarbonyl Ene Reaction 3.1 Single-Pot Nitrosocarbonyl Ene Reactions 3.2 Copper-Catalyzed Aerobic Oxidation for the Nitrosocarbonyl Ene Reaction 4 The Hetero-Diels-Alder Reaction as a Platform for Studying Aerobic Oxidation 5 Dual Catalysis and α-Functionalization Reactions 5.1 α-Amination Reaction of β-Keto Esters 5.2 α-Oxygenation Reaction of β-Keto Esters 6 The Future of Nitroso Chemistry [ABSTRACT FROM AUTHOR]

The acid-catalyzed rearrangement of furylcarbinols is utilized to access 4,5-substituted cyclopentenones. This cascade transformation began with implementing anilines, as an alternative nucleophile to water as used in the Piancatelli rearrangement, and has currently progressed through an intramolecular rearrangement to the use of alcohols as the nucleophile [ABSTRACT FROM AUTHOR]

A molecular rearrangement of 5,5-spirocyclic cyclopentenones to 5,6-fused cyclopentenones catalyzed by Amberlyst®15 is described. This work emphasizes the utility of renewable resources, such as furfural, that can be transformed into a variety of valuable products. It also highlights the viability of 5,5-spirocycles as intermediates en route to 5,6-fused cyclopentenones. [ABSTRACT FROM AUTHOR]

Two complementary approaches are presented for the synthesis of the quinone chromophores of the naphthoquinone ansamycins and related natural products. The first involves the use of an improved protocol for the manganese(III) acetate mediated cyclization of 5-aryl-1,3-dicarbonyl compounds to β-naphthols, leading to the simple, scalable preparation of building blocks suitable for the synthesis of naturally occurring aminonaphthoquinones. The second approach involves the Diels-Alder reaction of a series of new, ester-containing Danishefsky-type dienes with N-protected aminobenzoquinones to allow more expeditious access to similar intermediates. [ABSTRACT FROM AUTHOR]

Highly reactive acylnitroso species are generated from hydroxamic acids (I) via photoredox catalysis. [ABSTRACT FROM AUTHOR]

The Piancatelli rearrangement of a small series of furylcarbinols is examined. [ABSTRACT FROM AUTHOR]

An abstract of the article "Lewis Acid Catalyzed Rearrangement of Furylcarbinols: The Aza- and Oxa-Piancatelli Cascade Reaction" by Leoni I. Palmer and colleagues is presented.

Review: 37 refs.+subrefs. [ABSTRACT FROM AUTHOR]

5,5-Spirocyclic cyclopentenones undergo Amberlyst-15-catalyzed ring opening/ring closure rearrangement to form tetrahydropyrans (II) and (IV). [ABSTRACT FROM AUTHOR]

The observed rate of reaction in the dysprosium triflate catalyzed aza-Piancatelli rearrangement is controlled by a key off-cycle binding between aniline and catalyst. Deconvoluting the role of these ancillary species greatly broadens our understanding of factors affecting the productive catalytic pathway. We demonstrate that the rate of reaction is controlled by initial competitive binding between the furylcarbinol and nitrogen nucleophile using either a Brønsted or Lewis acid catalyst and that the resulting rearrangement proceeds without involving the Bronsted and Lewis acid catalyst. This shows conclusively that the rate-controlling step and selectivity of reaction are decoupled. [ABSTRACT FROM AUTHOR]

A novel synthesis of hydroxylamine-substituted cyclopentenones via aza-Piancatelli rearrangement of furylcarbinols with hydroxylamines is reported. [ABSTRACT FROM AUTHOR]

A high O-selectivity is observed in this nitrosocarbonyl aldol reaction. [ABSTRACT FROM AUTHOR]