C-H functionalization enabled by multiple isocyanides.

Past decades have witnessed significant advance of isocyanides as a class of versatile organic synthons as well as their broad applications in multi-component reactions (MCRs) and other tandem reactions. Reactions involving multiple isocyanides allow the construction of molecules with further diversification and complexity, while C-H functionalization emphasizes the advantages of high atom economy, broad substrate availability and great synthetic efficiency. This promising synergistic strategy of C-H functionalization involving multiple isocyanides provides a variety of valuable synthetic methods for organic chemists' toolbox and offers considerable potential in pharmaceutical chemistry and materials science as well. The present review outlines in detail various reaction types of C-H functionalization enabled by multiple isocyanides, and the relevant mechanistic rationale is discussed.

Active Fault Isolation for Multimode Fault Systems Based on a Set Separation Indicator.

This paper considers the active fault isolation problem for a class of uncertain multimode fault systems with a high-dimensional state-space model. It has been observed that the existing approaches in the literature based on a steady-state active fault isolation method are often accompanied by a large delay in making the correct isolation decision. To reduce such fault isolation latency significantly, this paper proposes a fast online active fault isolation method based on the construction of residual transient-state reachable set and transient-state separating hyperplane. The novelty and benefit of this strategy lies in the embedding of a new component called the set separation indicator, which is designed offline to distinguish the residual transient-state reachable sets of different system configurations at any given moment. Based on the results delivered by the set separation indicator, one can determine the specific moments at which the deterministic isolation is to be implemented during online diagnostics. Meanwhile, some alternative constant inputs can also be evaluated for isolation effects to determine better auxiliary excitation signals with smaller amplitudes and more differentiated separating hyperplanes. The validity of these results is verified by both a numerical comparison and an FPGA-in-loop experiment.

Synthesis of ß-Carbonyl α-Iminoamides by Double Insertion of Isocyanides into Aldehydes.

An unprecedented trimethylsilyl trifluoromethanesulfonate (TMSOTf)-promoted selective double insertion of isocyanides into aldehydes was developed, providing an efficient protocol for synthetically challenging ß-carbonyl α-iminoamides. The given approach is applicable for a diverse selection of readily accessible aldehydes, along with isocyanides serving as essential precursors for "amide" and "imine" scaffolds. The versatile transformations of the given products were demonstrated, and the pivotal intermediates for the plausible mechanism were identified.

Triple-Consecutive Isocyanide Insertions with Aldehydes: Synthesis of 4-Cyanooxazoles.

An efficient TMSOTf-promoted selective triple consecutive insertions of tert-butyl isocyanide into aldehydes has been developed, affording pharmacological interesting 4-cyanooxazoles in high yields in a one pot manner. The given method encompasses a wide range of substrates with tert-butyl isocyanide serving as sources of critical "CN" and "C-N═C" moieties. The versatile transformations of the resulting 4-cyanooxazoles were demonstrated. The key reaction intermediates for plausible mechanisms were determined.

Direct Nitration of Vinylcycles with Copper Nitrate.

A direct nitration of vinylcyclopropanes is disclosed with Cu(NO3)2 and KI in a regio- and stereoselective manner to afford nitroalkenes efficiently, where the cyclopropane skeleton was retained. The given method could be extended to other vinylcycles as well as biomolecule derivatives with wide substrate scope, good functionality tolerance, and efficient synthesis modularity. Further transformations illustrated the obtained products as versatile building blocks in organic synthesis. The proposed ionic pathway could account for the untouched small ring and the effect of KI during the reaction.