Catalytic beta-boration/oxidation of 1-azadienes

Alkoxide activation of tetra-alkoxy diboron reagents in C-B bond formation: a decade of unpredictable reactivity

Any attempt to facilitate a new generation of C-B bonds represents a useful tool in organic synthesis. In addition, if that approach highlights the nucleophilic character of boryl moieties in the absence of transition metal complexes, the challenge to create new reactive platforms becomes an opportunity. We have been deeply involved in the experimental and theoretical validation of C-B bond formation by means of alkoxide activation of tetra-alkoxy diboron reagents and here is presented a convenient guide to understand the concept and the applications.

Recent advances in Cu-catalyzed C(sp3)-Si and C(sp3)-B bond formation

Numerous reactions generating C-Si and C-B bonds are in focus owing to the importance of incorporating silicon or boron into new or existing drugs, in addition to their use as building blocks in cross-coupling reactions en route to various targets of both natural and unnatural origins. In this review, recent protocols relying on copper-catalyzed sp3 carbon-silicon and carbon-boron bond-forming reactions are discussed.

Theoretical study on homolytic B–B cleavages of diboron(4) compounds

The B–B BDEs of diboron(4) compounds and the Pt–B and Cu–B BDEs of their corresponding complexes were investigated by SOGGA11-X method.

Diboron(4) Compounds: From Structural Curiosity to Synthetic Workhorse

Although known for over 90 years, only in the past two decades has the chemistry of diboron(4) compounds been extensively explored. Many interesting structural features and reaction patterns have emerged, and more importantly, these compounds now feature prominently in both metal-catalyzed and metal-free methodologies for the formation of B-C bonds and other processes.

Synthesis of 1H-azadienes and application to one-pot organic transformations

1H-Azadienes were synthesized from allyl azides by ruthenium catalysis under mild and neutral conditions. Applications of the 1H-azadienes were demonstrated for the one-pot synthesis of nitrogen containing organic compounds.

sp(2)-sp(3) diboranes: astounding structural variability and mild sources of nucleophilic boron for organic synthesis

Despite the widespread use of organoborane reagents in organic synthesis and catalysis, a major challenge still remains: very few boron-centered nucleophiles exist for the direct construction of B-C bonds. Perhaps the most promising emerging solution to this problem is the use of sp(2)-sp(3) diboranes, in which one boron atom of a conventional diborane(4) is quaternised by either a neutral or anionic nucleophile. These compounds, either isolated or generated in situ, serve as relatively mild and convenient sources of the boryl anion [BR2](-) for use in organic synthesis and have already proven their efficacy in metal-free as well as metal-catalysed borylation reactions. This Feature article documents the history of sp(2)-sp(3) diborane synthesis, their properties and surprising structural variability, and their burgeoning utility in organic synthesis.

Asymmetric boron conjugate addition to α,β-unsaturated carbonyl compounds catalyzed by CuOTf/Josiphos under non-alkaline conditions

The asymmetric boron conjugate addition onto α,β-unsaturated ketones and esters has been developed by using the CuOTf/Josiphos complex as the catalyst under non-alkaline conditions.

One-pot catalytic asymmetric borylation of unsaturated aldehyde-derived imines; functionalisation to homoallylic boronate carboxylate ester derivatives

The β-borylation reaction of α,β-unsaturated aldehyde-derived imines, formed in situ, has been studied using a one-pot methodology, as a route to homoallylic boronates through the β-boryl aldehydes.

Asymmetric metal free β-boration of α,β-unsaturated imines assisted by (S)-MeBoPhoz

The adduct [MeO → Bpin–Bpin]⁻ efficiently mediates the β-boration of α,β-unsaturated imines formed in situ.

A one-pot diastereoselective self assembly of C-stereogenic copper(I) diphosphine clusters

C-chirogenic diphosphine-based clusters with 8-membered "chairlike" Cu4Cl4L2 and 12-membered "drumlike" Cu6Cl6L3 (L = diphosphine) frameworks were prepared in one-pot syntheses from chiral diphosphines, which were generated in situ via the double hydrophosphination reaction in excellent enantio- and diastereoselectivity. Excellent control over the final molecular architecture of the cluster (drum vs chair) could be achieved by the judicious selection of the source of the copper atoms employed in the synthetic protocol. Each cluster was characterized by single-crystal X-ray crystallography, (1)H, (13)C, and (31)P{(1)H} NMR spectroscopy. The synthesized clusters were found to exhibit catalytic activity in the hydroboration reaction of α,β-unsaturated enones with excellent yields albeit with low enantioselectivity.

Catalytic methodologies for the β-boration of conjugated electron deficient alkenes

The area of boron conjugate addition via diboration (β-boration) has grown rapidly since the first examples appeared in the late 1990s. This article aims to give a comprehensive review of the current advances in β-boration (of electron deficient alkenes), providing a commentary upon the development of the asymmetric version. To date, many mechanistic models have been put forward to explain the experimental observations and this review surveys some of these key ideas. Recently, the development of organocatalytic methodologies that facilitate β-boration have also been demonstrated and current ideas regarding the mechanisms of such processes are examined.