Ni-catalyzed cross-coupling reaction of aryl chlorides with arylboronic acids in IPA without using a reducing reagent

Transition-metal-catalyzed Suzuki-Miyaura cross-coupling reactions: a remarkable advance from palladium to nickel catalysts

In the transition-metal-catalyzed cross-coupling reactions, the use of the first row transition metals as catalysts is much more appealing than the precious metals owing to the apparent advantages such as cheapness and earth abundance. Within the last two decades, particularly the last five years, explosive interests have been focused on the nickel-catalyzed Suzuki-Miyaura reactions. This has greatly advanced the chemistry of transition-metal-catalyzed cross-coupling reactions. Most notably, a broad range of aryl electrophiles such as phenols, aryl ethers, esters, carbonates, carbamates, sulfamates, phosphates, phosphoramides, phosphonium salts, and fluorides, as well as various alkyl electrophiles, which are conventionally challenging, by applying palladium catalysts can now be coupled efficiently with boron reagents in the presence of nickel catalysts. In this review, we would like to summarize the progress in this reaction.

Nickel(II) hydride and fluoride pincer complexes and their reactivity with Lewis acids BX3·L (X = H, L = thf; X = F, L = Et2O)

Reaction of the pincer hydride complex ((tBu)PCP)Ni(H) [(tBu)PCP = 2,6-C(6)H(3)(CH(2)P(t)Bu(2))(2)] with BH(3)·thf in THF at 190 K generates the corresponding borohydride complex ((tBu)PCP)Ni(BH(4)). The kinetically stable (but thermodynamically unstable) species undergoes reversible borane loss. The related fluoride complex ((tBu)PCP)Ni(F) shows the same reactivity towards BF(3)·Et(2)O, producing ((tBu)PCP)Ni(BF(4)) as the main final product. The processes were followed through multinuclear NMR spectroscopy and DFT calculations, at the M06//6-31+G(d,p) level of theory.

Rapid nickel-catalyzed Suzuki-Miyaura cross-couplings of aryl carbamates and sulfamates utilizing microwave heating

High-speed and scalable nickel-catalyzed cross-coupling of arylboronic acids with aryl carbamates and sulfamates is achieved by using sealed-vessel microwave processing.

THEORETICAL INVESTIGATION ON THE REACTION MECHANISM OF CuI-CATALYZED FORMATION OF ETHYL 2-PHENYLACETOACETATE

The reaction mechanism of CuI -catalyzed formation of ethyl 2-phenylacetoacetate by arylation of ethyl acetoacetate has been investigated by density functional theory (DFT) using Becke's three-parameter nonlocal exchange functional and the Lee, Yang, and Parr nonlocal correlation functional (B3LYP). The geometries of the reactants, intermediates, transition states, and products have been optimized and verified by means of vibration frequency calculations. According to our assumption, this reaction can be divided into two stages. The rate-determining step is found to be the 3 → 4-TS procedure, which is the first procedure of stage 1. The low energy barrier of 39.85 kcal/mol indicates that this reaction can be carried out, which is in accordance with the experimental facts. For comparison, we have investigated the reaction mechanism of the same chemical reaction without CuI catalyst, whose energy barrier of rate-determining step is 212.76 kcal/mol higher than that with CuI catalyst. This fact suggests that CuI catalyst accelerates the reaction by remarkably lowering the energy barrier. The solvation effects on the barriers of the reaction are important. But the energetic order in DMSO solvent seems to be almost the same as that in gas-phase, which indicates that our conclusion achieved in gas-phase is believable. Our findings reveal the microscopic catalytic mechanism of CuI and are in agreement with the experimental facts.