Copper-catalyzed silylation of p-quinone methides: New entry to dibenzylic silanes

An efficient and general copper(i)-catalyzed silylation of p-quinone-methides is described. Non-symmetric dibenzylic silanes are obtained in high yields under mild reaction conditions. These compounds can be used as bench-stable benzylic carbanion precursorsWe thank the European Research Council (ERC-337776) and MINECO (CTQ2012-35957) for financial support. M. T. and A. P. thank MICINN for RyC and JdC contract

Stereoselective traceless borylation–allenation of propargylic epoxides: dual role of the copper catalyst

This is the peer reviewed version of the following article: Chemistry: A European Journal 23.69 (2017): 17478 –17481, which has been published in final form at http://doi.org/10.1002/chem.201705019. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-ArchivingChiral α-allenols are prepared with high diastereocontrol through an unprecedented and spontaneous β-oxygen elimination of an α-epoxy vinyl boronate. Stochiometric experiments and DFT calculations support a dual role of the copper catalyst, which orchestrates the hydroboration and the syn-elimination stepThe European ResearchCouncil (ERC-337776) and MINECO (CTQ2016-78779-R) for financial support M.T.thanks MICINNfor a RyC contrac

Enantiospecific Synthesis of 1,3-Disubstituted Allenes from Propargylic Carbonates through a Borylation-1,2-Elimination Process

An array of enantioenriched vinyl boronates bearing an allylic carbonate moiety have been prepared through selective hydroboration of propargyl carbonates. Treatment of these vinyl boronates with TBAF in THF affords enantioenriched 1,3- disubstituted allenes through a novel 1,2-anti elimination in good yields and high enantiospecificitiesWe thank MINECO (CTQ2016-78779-R) and MICINN (PID2019-107380GB I00) for financial suppor

Organocatalytic enantioselective Friedel-Crafts alkylation of 1-naphthol derivatives and activated phenols with ethyl trifluoropyruvate

An organocatalytic enantioselective Friedel-Crafts alkylation of a series of substituted 1‐naphthol derivatives and activated phenols with ethyl trifluoropyruvate, catalyzed by a quinine‐derived squaramide, is presented. Good yields and high to excellent enantioselectivities of the Friedel-Crafts alkylation products were obtained

Switchable synthesis of Z-homoallylic boronates and E-allylic boronates by enantioselective copper-catalyzed 1,6-boration

The enantioselective Cu-catalyzed 1,6-boration of (E,E) α,β,γ,δ-unsaturated ketones is described, which gives homoallylic boronates with high enantiomeric purity and unexpectedly high Zselectivity. By changing the solvent, the outcome can be altered to give E-allylic boronates

Nuevas reacciones de borilación catalizadas por cobre en la síntesis de boranatos dibencílicos y alenos

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid. Facultad de Ciencias. Departamento de Química Orgánica. Fecha de lectura: 16-07-2018Esta tesis tiene embargado el acceso al texto completo hasta el 16-01-202

Selective Reductive Dimerization of CO 2 into Glycolaldehyde

International audienceThe selective dimerization of CO2 into glycolaldehyde is achieved in a one-pot two-step process via formaldehyde as a key intermediate. The first step concerns the iron-catalyzed selective reduction of CO2 into formaldehyde via formation and controlled hydrolysis of a bis(boryl)acetal compound. The second step concerns the carbene-catalyzed C–C bond formation to afford glycolaldehyde. Both carbon atoms of glycolaldehyde arise from CO2 as proven by the labeling experiment with 13CO2. This hybrid organometallic/organic catalytic system employs mild conditions (1 atm of CO2, 25 to 80 °C in less than 3 h) and low catalytic loadings (1 and 2.5%, respectively). Glycolaldehyde is obtained in 53% overall yield. The appealing reactivity of glycolaldehyde is exemplified (i) in a dimerization process leading to C4 aldose compounds and (ii) in a tri-component Petasis–Borono–Mannich reaction generating C–N and C–C bonds in one process

Borohydride Compounds Catalyze the Selective 4e – Reduction of CO 2 with 9-BBN

International audienceThe selective double hydroboration of CO2 into bis(boryl)acetal (BBA) is a challenging yet appealing reduction process since BBA can be used as a versatile C1 and Cn sources for the synthesis of value-added products. In the present study, we demonstrate that simple borohydride compounds are efficient and selective catalysts for the synthesis of BBA when using 9-borabicyclo(3.3.1)nonane (9-BBN) as a reductant. The experimental and theoretical investigations show that while the borohydride species catalyzes the first reduction step of CO2 into formoxyborane (2e– reduction intermediate), the observed 4e– reduction selectivity is mostly due to the ability of 9-BBN to reduce the formoxyborane into BBA without a catalyst. Notably, 0.2 mol % of LiH2BBN catalyzed the hydroboration of CO2 with 9-BBN as a reductant into the corresponding BBA in 77% yield with TON and TOF of 385 and 196 h–1, respectively. The simplicity of borohydride contrasts with the more elaborate catalytic systems used so far for the 4e– reduction of CO2