Allylic activation across an Ir–Sn heterobimetallic catalyst: nucleophilic substitution and disproportionation of allylic alcohol

Alcohols as Substrates in Transition-Metal-Catalyzed Arylation, Alkylation, and Related Reactions

Alcohols are abundant and attractive feedstock molecules for organic synthesis. Many methods for their functionalization require them to first be converted into a more activated derivative, while recent years have seen a vast increase in the number of complexity-building transformations that directly harness unprotected alcohols. This Review discusses how transition metal catalysis can be used toward this goal. These transformations are broadly classified into three categories. Deoxygenative functionalizations, representing derivatization of the C-O bond, enable the alcohol to act as a leaving group toward the formation of new C-C bonds. Etherifications, characterized by derivatization of the O-H bond, represent classical reactivity that has been modernized to include mild reaction conditions, diverse reaction partners, and high selectivities. Lastly, chain functionalization reactions are described, wherein the alcohol group acts as a mediator in formal C-H functionalization reactions of the alkyl backbone. Each of these three classes of transformation will be discussed in context of intermolecular arylation, alkylation, and related reactions, illustrating how catalysis can enable alcohols to be directly harnessed for organic synthesis.

Direct deoxygenation of active allylic alcohols via metal-free catalysis

Direct metal-free deoxygenation of highly active allylic alcohols catalyzed by a Brønsted acid was achieved, which avoids tedious reaction steps and eliminates metal contamination. By examining a series of Brønsted...

Production of Alkyl Aryl Sulfides from Aromatic Disulfides and Alkyl Carboxylates via a Disilathiane-Disulfide Interchange Reaction

The results of this study show that disilathiane is an effective mediator in the synthesis of alkyl aryl sulfides with disulfides and alkyl carboxylates. Mechanistic studies suggest that disilathiane promotes cleavage of the sulfur-sulfur bond of disulfides to generate thiosilane as a key intermediate. Diselenides were also applicable to this transformation to produce the corresponding selenides.

H2 and carbon-heteroatom bond activation mediated by polarized heterobimetallic complexes

The field of heterobimetallic chemistry has rapidly expanded over the last decade. In addition to their interesting structural features, heterobimetallic structures have been found to facilitate a range of stoichiometric bond activations and catalytic processes. The accompanying review summarizes advances in this area since January of 2010. The review encompasses well-characterized heterobimetallic complexes, with a particular focus on mechanistic details surrounding their reactivity applications.

Learning To Predict Reaction Conditions: Relationships between Solvent, Molecular Structure, and Catalyst

Reaction databases provide a great deal of useful information to assist planning of experiments but do not provide any interpretation or chemical concepts to accompany this information. In this work, reactions are labeled with experimental conditions, and network analysis shows that consistencies within clusters of data points can be leveraged to organize this information. In particular, this analysis shows how particular experimental conditions (specifically solvent) are effective in enabling specific organic reactions (Friedel-Crafts, Aldol addition, Claisen condensation, Diels-Alder, and Wittig), including variations within each reaction class. Network analysis shows data points for reactions tend to break into clusters that depend on the catalyst and chemical structure. This type of clustering, which mimics how a chemist reasons, is derived directly from the network. Therefore, the findings of this work could augment synthesis planning by providing predictions in a fashion that mimics human chemists. To numerically evaluate solvent prediction ability, three methods are compared: network analysis (through the k-nearest neighbor algorithm), a support vector machine, and a deep neural network. The most accurate method in 4 of the 5 test cases is the network analysis, with deep neural networks also showing good prediction scores. The network analysis tool was evaluated by an expert panel of chemists, who generally agreed that the algorithm produced accurate solvent choices while simultaneously being transparent in the underlying reasons for its predictions.

Crystal structure of (1S,3R,8R,9R)-2,2-di-chloro-3,7,7-tri-methyl-10-methylenetri-cyclo-[6.4.0.0(1,3)]dodecan-9-ol

The title compound, C16H24Cl2O, was synthesized by treating (1S,3R,8S,9R,10S)-2,2-di-chloro-3,7,7,10-tetra-methyl-9,10-ep-oxy-tri-cyclo-[6.4.0.0(1,3)]dodecane with a concentrated solution of hydro-bromic acid. It is built up from three fused rings: a cyclo-heptane ring, a cyclo-hexyl ring bearing alkene and hy-droxy substituents, and a cyclo-propane ring bearing two chlorine atoms. The asymmetric unit contains two mol-ecules linked by an O-H⋯O hydrogen bond. In the crystal, further O-H⋯O hydrogen bonds build up an R 4 (4)(8) cyclic tetra-mer. One of the mol-ecules presents disorder that affects the seven-membered ring. In both mol-ecules, the six-membered rings display a chair conformation, whereas the seven-membered rings display conformations inter-mediate between boat and twist-boat for the non-disordered mol-ecule and either a chair or boat and twist-boat for the disordered mol-ecule owing to the disorder. The absolute configuration for both mol-ecules is 1S,3R,8R,9R and was deduced from the chemical pathway and further confirmed by the X-ray structural analysis.

Recent advances in heterobimetallic catalysis across a “transition metal–tin” motif

This review focuses on the efficacy of catalysts, based on a transition metal–tin (TM–Sn) motif and crafted on a single scaffold, in mediating a wide variety of organic transformations.

Copper-catalysed α-selective allylic alkylation of heteroaryllithium reagents

2-Allyl-substituted thiophenes and furans are synthesised efficiently in a direct procedure using 2-heteroaryllithium reagents and allyl bromides and chlorides catalysed by ligand-free copper(i). The reactions take place under mild conditions, with excellent α-selectivity, high functional group tolerance and good yields for the SN2 products.