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Monoprotonated homoleptic complex of cobalt(ii) with 4′-pyridyl-2,2′;6′,2′′-terpyridine ligand is an efficient precatalyst for hydroboration of styrene derivatives with Markovnikov selectivity, displaying turnover frequencies up to 47 000 h⁻¹.

 

A facile epoxide ring-opening hydroboration reaction catalysed by an active vanadium complex supported by a redox-active terpyridine ligand is reported for the synthesis of secondary alcohols under mild conditions.

 

An ionic metal–organic-framework (MOF) containing nanoscale channels was readily assembled from ditopic 4′-pyridyl-2,2′:6′,2′′-terpyridine (pytpy) and a simple iron( ii ) salt. X-ray structural analysis revealed a two-dimensional grid-like framework assembled by classic octahedral (pytpy) 2 Fe II cations as linkers (with pytpy as a new ditopic pyridyl ligand) and octa-coordinate FeCl 2 centers as nodes. The layer-by-layer assembly of the 2-D framework resulted in the formation of 3-D porous materials consisting of nano-scale channels. The charges of the cationic framework were balanced with anionic Cl 3 FeOFeCl 3 in its void channels. The new Fe-based MOF material was employed as a precatalyst for syn -selective hydroboration of alkynes under mild, solvent-free conditions in the presence of an activator, leading to the synthesis of a range of trans -alkenylboronates in good yields. The larger scale applicability and recyclability of the new MOF catalyst was further explored. This represents a rare example of an ionic MOF material that can be utilized in hydroboration catalysis. 

A new diplumbane, namely [Pb(CH 2 SiMe 3 ) 3 ] 2 , was synthesized and structurally characterized. This group 14 element compound was found to catalyse the hydroboration of ketones and aldehydes under mild conditions without the use of additives and solvents, leading to the synthesis of a range of alcohols in high yields after hydrolysis. 

A ditopic nitrogen ligand (E)-N′-(pyridin-4-ylmethylene)isonicotinohydrazide (L) containing both divergent pyridyl coordination sites and a hydrogen-bonding hydrazide–hydrazone moiety was synthesized. The Co(NCS)2-mediated self-assembly of L has resulted in the synthesis of a novel 3-dimensional (3D) supramolecular framework (1) that features both coordination and hydrogen bonding interactions. X-ray structural analysis reveals the formation and coordination mode of 1 in the solid state. The rational utilization of coordination bonds and hydrogen bonding interactions is confirmed and responsible for constructing the 3D materials. Catalytic studies using 1 in the presence of an activator are performed for the hydroboration and hydrosilylation reactions of ketones and aldehydes, and the results are compared with previously reported cobalt-based polymeric catalysts. 

Molecular complexes of vanadium catalyze cis-selective anti-Markovnikov hydroboration of alkynes to generate vinyl boronate esters with appreciable turnover numbers of up to 4000 at room temperature. This represents the first example of the use of vanadium in homogeneous catalytic hydroboration of alkynes. The method is tolerant to various functional groups, including C═C double bonds. Accordingly, 1-hexen-5-yne can be quantitatively and selectively reduced at the triple bond, leaving the double bond unaffected. Preliminary computational analysis of the catalytic cycle reveals both two-state reactivity and previously unknown complexity associated with the redox-active ligand. Specifically, it was found that the ligand can shuttle up to two electrons back-and-forth to and from the metal, which thus adapts three different oxidation states on the catalytic reaction coordinate. 

A modular platform for facile access to 1,2,3,9‐tetrahydro‐4H‐carbazol‐4‐ones (H₄‐carbazolones) and 3,4‐dihydrocyclopenta[b]indol‐1(2H)‐ones (H₂‐indolones) is described. The requisite 6‐ and 5‐membered 2‐arylcycloalkane‐1,3‐dione precursors were readily obtained through a Cu‐catalyzed arylation of 1,3‐cyclohexanediones or by a ring expansion of aryl succinoin derivatives. Enolization of one carbonyl group in the diones, conversion to a leaving group, and subsequent azidation gave 2‐aryl‐3‐azidocycloalk‐2‐en‐1‐ones. This two‐step, one‐pot azidation is highly regioselective with unsymmetrically substituted 2‐arylcyclohexane‐1,3‐diones. The regioselectivity, which is important for access to single isomers of 3,3‐disubstituted carbazolones, was analyzed mechanistically and computationally. Finally, a Rh‐catalyzed nitrene/nitrenoid insertion into theorthoC−H bond of the aryl moiety gave the H₄‐carbazolones and H₂‐indolones. One carbazolone was elaborated to an intermediate reported in the total synthesis ofN‐decarbomethoxychanofruticosinate, (−)‐aspidospermidine, (+)‐kopsihainanine A. With 2‐phenylcycloheptane‐1,3‐dione, prepared from cyclohexanone and benzaldehyde, the azidation reaction was readily accomplished. However, the Rh‐catalyzed reaction unexpectedly led to a labile but characterizable azirine rather than the indole derivative. Computations were performed to understand the differences in reactivities of the 5‐ and 6‐membered 2‐aryl‐3‐azidocycloalk‐2‐en‐1‐ones in comparison to the 7‐membered analogue, and to support the structural assignment of the azirine.