Catalytic dehydrogenative cross-coupling: forming carbon-carbon bonds by oxidizing two carbon-hydrogen bonds

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Aryl-aryl bond formation one century after the discovery of the Ullmann reaction.

The direct functionalization of C-H bonds in organic compounds has recently emerged as a powerful and ideal method for the formation of carbon-carbon and carbon-heteroatom bonds. This Review provides an overview of C-H bond functionalization strategies for the rapid synthesis of biologically active compounds such as natural products and pharmaceutical targets.

C-H bond functionalization: emerging synthetic tools for natural products and pharmaceuticals

This Review covers recent progress on near-infrared fluorescence imaging for preclinical animal studies and clinical diagnostics and interventions.

Near-infrared fluorophores for biomedical imaging

Since the discovery of organic azides by Peter Griess more than 140 years ago, numerous syntheses of these energy-rich molecules have been developed. In more recent times in particular, completely new perspectives have been developed for their use in peptide chemistry, combinatorial chemistry, and heterocyclic synthesis. Organic azides have assumed an important position at the interface between chemistry, biology, medicine, and materials science. In this Review, the fundamental characteristics of azide chemistry and current developments are presented. The focus will be placed on cycloadditions (Huisgen reaction), aza ylide chemistry, and the synthesis of heterocycles. Further reactions such as the aza-Wittig reaction, the Sundberg rearrangement, the Staudinger ligation, the Boyer and Boyer-Aube rearrangements, the Curtius rearrangement, the Schmidt rearrangement, and the Hemetsberger rearrangement bear witness to the versatility of modern azide chemistry.

Organic Azides: An Exploding Diversity of a Unique Class of Compounds

Many natural products contain bicyclo[n.3.1]alkane substructures with a functionalized quaternary bridgehead carbon atom, sometimes fused with additional rings. They include the bicyclo[3.3.1]alkane derivative hyperforin, considered to be the main active component of the anti‐depressant plant Hypericum perforatum (St. John'swort), and some members of the family of cyanobacterial secondary metabolites known as welwitindolinones, most notably N‐ methylwelwistatin, which contain bicyclo[4.3.1]decane structural fragments. As part of an ongoing research programme inourgroup aimingat thedevelopment ofanionic domino reactions for the synthesis of biologically relevant targets, we have developed a general protocol allowing access to bicyclo [n.3.1]alkane systems bearing a bridgehead nitrogen function via aMichael‐nitroaldol sequence andhave studied the application of this strategy to the synthesis of the tetracyclic welwistatin core. The remarkably high diastereoselectivity of this domino process drew our attention, and in the present work we describe the application of H‐, C‐, and 2D‐NMR spectral data to the structural analysis of bicyclo[n.3.1]alkane derivatives. While the NMR‐based structural study of derivatives of the bicyclo[3.2.1]alkane system has been described in the literature, toour knowledge, there is noaccountof the systematic application of thesemethods to the study of a full series of bicyclo[n.3.1]alkane derivatives, with varying values of n, probably owing to the lackof a general synthetic access to these systems. We describe here the study by H‐, C‐, and 2D‐ NMR techniques of compounds 2a‐18, obtained from α‐ nitrocyclalkanones 1 by our previously published method, and the application of spectral data to their conformational and configurational assignment. The minor diastereomers 2b and 19 were also studied for comparison purposes (Figure 1).

A systematic 1H- and 13C-NMR spectral analysis of bicyclo[n.3.1]alkanone systems: Determination of the relative configuration of the stereogenic centres and conformation of the six-membered ring

J. Carlos Menéndez

Papers

A systematic 1H- and 13C-NMR spectral analysis of bicyclo[n.3.1]alkanone systems: Determination of the relative configuration of the stereogenic centres and conformation of the six-membered ring