Much has been written about theory and practice in the law, and the tension between practitioners and theorists. Judges do not cite theoretical articles often; they rarely "apply" theories to particular cases. These arguments are not revisited. Instead the Essay explores the working and interaction of theory and practice, practitioners and theorists. The Essay starts with a story about solving a legal issue using our intellectual tools - theory, practice, and their progenies: experience and "gut." Next the Essay elaborates on the nature of theory, practice, experience and "gut." The third part of the Essay discusses theories that are helpful to practitioners and those that are less helpful. The Essay concludes that practitioners theorize, and theorists practice. They use these intellectual tools differently because the goals and orientations of theorists and practitioners, and the constraints under which they act, differ. Theory, practice, experience and "gut" help us think, remember, decide and create. They complement each other like the two sides of the same coin: distinct but inseparable.

Of Theory and Practice

Organic reactions that involve the direct functionalization of non-activated C–H bonds represent an attractive class of transformations which maximize atom- and step-economy, and simplify chemical synthesis. Due to the high stability of C–H bonds, these processes, however, have most often required harsh reaction conditions, which has drastically limited their use as tools for the synthesis of complex organic molecules. Following the increased understanding of mechanistic aspects of C–H activation gained over recent years, great strides have been taken to design and develop new protocols that proceed efficiently under mild conditions and duly benefit from improved functional group tolerance and selectivity. In this review, we present the current state of the art in this field and detail C–H activation transformations reported since 2011 that proceed either at or below ambient temperature, in the absence of strongly acidic or basic additives or without strong oxidants. Furthermore, by identifying and discussing the major strategies that have led to these improvements, we hope that this review will serve as a useful conceptual overview and inspire the next generation of mild C–H transformations.

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Mild metal-catalyzed C–H activation: examples and concepts

Research and industrial interest in radical C–H activation/radical cross-coupling chemistry has continuously grown over the past few decades. These reactions offer fascinating and unconventional approaches toward connecting molecular fragments with high atom- and step-economy that are often complementary to traditional methods. Success in this area of research was made possible through the development of photocatalysis and first-row transition metal catalysis along with the use of peroxides as radical initiators. This Review provides a brief and concise overview of the current status and latest methodologies using radicals or radical cations as key intermediates produced via radical C–H activation. This Review includes radical addition, radical cascade cyclization, radical/radical cross-coupling, coupling of radicals with M–R groups, and coupling of radical cations with nucleophiles (Nu).

Recent Advances in Radical C-H Activation/Radical Cross-Coupling.

Recent Advances of Catalytic Asymmetric 1,3-Dipolar Cycloadditions

Conventional methods for carrying out carbon–hydrogen functionalization and carbon–nitrogen bond formation are typically conducted at elevated temperatures, and rely on expensive catalysts as well as the use of stoichiometric, and perhaps toxic, oxidants. In this regard, electrochemical synthesis has recently been recognized as a sustainable and scalable strategy for the construction of challenging carbon–carbon and carbon–heteroatom bonds. Here, electrosynthesis has proven to be an environmentally benign, highly effective and versatile platform for achieving a wide range of nonclassical bond disconnections via generation of radical intermediates under mild reaction conditions. This review provides an overview on the use of anodic electrochemical methods for expediting the development of carbon–hydrogen functionalization and carbon–nitrogen bond formation strategies. Emphasis is placed on methodology development and mechanistic insight and aims to provide inspiration for future synthetic applications in the field of electrosynthesis.

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Electrochemical strategies for C-H functionalization and C-N bond formation.

Recent Advances in Radical Difunctionalization of Simple Alkenes

Copper/Manganese Cocatalyzed Oxidative Coupling of Vinylarenes with Ketones

Organocatalytic and metal-mediated asymmetric [3 + 2] cycloaddition reactions

A highly divergent de novo asymmetric synthesis of benzyl alpha-6-deoxyaltropyranoside, benzyl alpha-ascarylopyranoside, benzyl alpha-amicetopyranoside, and benzyl alpha-digitoxopyranoside has been achieved via a common pyranone intermediate. The routes rely upon a palladium(0)-catalyzed glycosylation reaction and corresponding post-glycosylation transformations. The control of the absolute and relative stereochemical configuration came from a Noyori reduction of 2-acylfuran and subsequent diastereoselective introduction of other stereogenic centers.

Yalan Xing

Papers

Recent Advances in Radical Difunctionalization of Simple Alkenes

Copper/Manganese Cocatalyzed Oxidative Coupling of Vinylarenes with Ketones

Organocatalytic and metal-mediated asymmetric [3 + 2] cycloaddition reactions

De Novo Asymmetric Synthesis of an α-6-Deoxyaltropyranoside as Well as its 2-/3-Deoxy and 2,3-Dideoxy Congeners

Unactivated C(sp3)–H Bond Functionalization of Alkyl Nitriles with Vinylarenes and Mechanistic Studies