Accelerating role of deaggregation agents in lithium-catalysed hydrosilylation of carbonyl compounds

Arenes participate in 1,3-dipolar cycloaddition with in situ-generated diazoalkenes

The venerable 1,3-dipolar cycloaddition has been widely used in organic synthesis for the construction of various heterocycles. However, in its century-long history, the simple and omnipresent aromatic phenyl ring has remained a stubbornly unreactive dipolarophile. Here we report 1,3-dipolar cycloaddition between aromatic groups and diazoalkenes, generated in situ from lithium acetylides and N-sulfonyl azides. The reaction results in densely functionalized annulated cyclic sulfonamide-indazoles that can be further converted into stable organic molecules that are important in organic synthesis. The involvement of aromatic groups in the 1,3-dipolar cycloadditions broadens the synthetic utility of diazoalkenes, a family of dipoles that have been little explored so far and are otherwise difficult to access. The process described here provides a route for the synthesis of medicinally relevant heterocycles and can be extended to other arene-containing starting materials. Computational examination of the proposed reaction pathway revealed a series of finely orchestrated bond-breaking and bond-forming events that ultimately lead to the annulated products.

Lithium anthraquinoids as catalysts in the ROP of lactide and caprolactone into cyclic polymers

New lithium anthraquinoids 2b–d active in the synthesis of cyclic PLA and cyclic PCL have been synthesized and fully characterized.

Molecular Main Group Metal Hydrides

This review serves to document advances in the synthesis, versatile bonding, and reactivity of molecular main group metal hydrides within Groups 1, 2, and 12-16. Particular attention will be given to the emerging use of said hydrides in the rapidly expanding field of Main Group element-mediated catalysis. While this review is comprehensive in nature, focus will be given to research appearing in the open literature since 2001.

Pd-catalyzed sp-sp3 cross-coupling of benzyl bromides using lithium acetylides

Organolithium-based cross-coupling reactions have emerged as an indispensable method to construct C–C bonds. These transformations have proven particularly useful for the direct and fast coupling of various organolithium reagents (sp, sp², and sp³) with aromatic (pseudo) halides (sp²). Here we present an efficient method for the cross-coupling of benzyl bromides (sp³) with lithium acetylides (sp). The reaction proceeds within 10 min at room temperature and can be performed in the presence of organolithium-sensitive functional groups such as esters, nitriles, amides and boronic esters. The potential application of the methodology is demonstrated in the preparation of key intermediates used in pharmaceuticals, chemical biology and natural products.

A fast and highly selective method for cross-coupling of benzyl bromides with lithium acetylides, proceeding at room temperature in 10 min while tolerating various organolithium-sensitive functional groups, is presented.

Alkali-Metal Mediation: Diversity of Applications in Main-Group Organometallic Chemistry

Organolithium compounds have been at the forefront of synthetic chemistry for over a century, as they mediate the synthesis of myriads of compounds that are utilised worldwide in academic and industrial settings. For that reason, lithium has always been the most important alkali metal in organometallic chemistry. Today, that importance is being seriously challenged by sodium and potassium, as the alkali-metal mediation of organic reactions in general has started branching off in several new directions. Recent examples covering main-group homogeneous catalysis, stoichiometric organic synthesis, low-valent main-group metal chemistry, polymerization, and green chemistry are showcased in this Review. Since alkali-metal compounds are often not the end products of these applications, their roles are rarely given top billing. Thus, this Review has been written to alert the community to this rising unifying phenomenon of "alkali-metal mediation".