Catalytic 1,3-Difunctionalisation of Organic Backbones through a Highly Stereoselective, One-Pot, Boron Conjugate-Addition/Reduction/Oxidation Process

Enantioselective zinc-mediated conjugate alkynylation of saccharin-derived 1-aza-butadienes

Diethylzinc and a bis(hydroxyl)malonamide ligand allow the first conjugate alkynylation of α,β-unsaturated imines. Excellent enatioselectivities are obtained with aliphatic alkynes.

Recent Advances in Metal-Catalyzed Asymmetric 1,4-Conjugate Addition (ACA) of Nonorganometallic Nucleophiles

The metal-catalyzed asymmetric conjugate addition (ACA) reaction has emerged as a general and powerful approach for the construction of optically active compounds and is among the most significant and useful reactions in synthetic organic chemistry. In recent years, great progress has been made in this area with the use of various chiral metal complexes based on different chiral ligands. This review provides comprehensive and critical information on the enantioselective 1,4-conjugate addition of nonorganometallic (soft) nucleophiles and their importance in synthetic applications. The literature is covered from the last 10 years, and a number of examples from before 2007 are included as background information. The review is divided into multiple parts according to the type of nucleophile involved in the reaction (such as C-, B-, O-, N-, S-, P-, and Si-centered nucleophiles) and metal catalyst systems used.

Copper-catalysed enantioselective Michael addition of malonic esters to β-trifluoromethyl-α,β-unsaturated imines

A diastereo- and enantioselective Michael addition of methyl malonate to β-trifluoromethyl unsaturated imines is presented.

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.

Copper-Catalyzed Borylative Aromatization of p-Quinone Methides: Enantioselective Synthesis of Dibenzylic Boronates

In this report, we establish that DM-Segphos copper(I) complexes are efficient catalysts for the enantioselective borylation of para-quinone methides. This method provides straightforward access to chiral monobenzylic and dibenzylic boronic esters, with enantiomeric ratios up to 96:4, using a commercially available chiral phosphine. Standard manipulations of the C–B bond afford a variety of chiral diaryl derivatives.

Chiral Cu(II)-catalyzed enantioselective β-borylation of α,β-unsaturated nitriles in water

The promising performance of copper(II) complexes was demonstrated for asymmetric boron conjugate addition to α,β-unsaturated nitriles in water. The catalyst system, which consisted of Cu(OAc)₂ and a chiral 2,2′-bipyridine ligand, enabled β-borylation and chiral induction in water. Subsequent protonation, which was accelerated in aqueous medium, led to high activity of this asymmetric catalysis. Both solid and liquid substrates were suitable despite being insoluble in water.

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.

Organocatalytic functionalisation through boron chemistry

Diboron reagents can be activated both, from a metal or free-metal context, and consequently the addition of boryl units to unsaturated substrates proceeds sometimes with complementary selectivity. We highlight here the power of boron chemistry to functionalize molecules and provide new routes towards challenging compounds.

A Cu(ii)-based strategy for catalytic enantioselective β-borylation of α,β-unsaturated acceptors

The unique nature and readily availability of Cu(v) species underscores the value of the Cu(v)-based catalyst over an array of well-documented Cu(i)-based catalysts.

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.

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.

1,1/1,2 Isomerisation in Lewis base adducts of B2cat2

The unexpected 1,1/1,2 isomerisation of the diolate in B₂cat₂ is observed on addition of Lewis bases.

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.

Total synthesis of fluoxetine and duloxetine through an in situ imine formation/borylation/transimination and reduction approach

We report efficient, catalytic, asymmetric total syntheses of both (R)-fluoxetine and (S)-duloxetine from α,β-unsaturated aldehydes conducting five sequential one-pot steps (imine formation/copper mediated β-borylation/transimination/reduction/oxidation) followed by the specific ether group formation which deliver the desired products (R)-fluoxetine in 45% yield (96% ee) and (S)-duloxetine in 47% yield (94% ee).