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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 enantiospecificities. [ABSTRACT FROM AUTHOR]

The hydroboration of CO2 into bis(boryl)acetal (BBA) compounds is an important transformation, since it enabled to selectively reduce CO2 by 4e‐and to subsequently use the BBA compounds as C1 and Cn sources. However, the influence of the nature of the boryl moieties on the reactivity of BBA compounds has not been evaluated so far. In the present study, four BBA compounds – including two new ones – were reacted with 2,6‐diisopropylaniline to afford the expected imine. Significant differences in the rate of the reaction from minutes to weeks have been observed depending on the BBA used, showing the importance of the nature of the boryl moieties. Theoretical investigations enabled to propose a mechanism involving the addition of the aniline to the BBA as the rate‐determining step and to determine that the steric hindrance of the BBA compounds is the main factor driving the rate of this condensation reaction. [ABSTRACT FROM AUTHOR]

Chiral 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 step. [ABSTRACT FROM AUTHOR]

The asymmetric synthesis of tricyclic compounds by the desymmetrization of cyclohexadienones is presented. The reaction tolerated a large variety of substituents at different positions of the cyclohexadienone, and heterocyclic rings of different sizes were accessible. Density functional theory calculations showed that the reaction proceeds through an asynchronous [4+2] cycloaddition. [ABSTRACT FROM AUTHOR]

The article offers information on the organocatalytic synthesis of 3,4-disubstituted pyrroles by a cascade of reactions. During the cascade of reactions, an adduct intermediates formation takes place before the 3,4-disusstituted pyrroles formation. The adducts then react with an amine and undergo a series of reactions to form the pyrroles.

Dihydroarylfuran skeletons are efficiently synthesized from (Z)-bromonitroalkenes and naphthol derivatives in good yields and excellent enantioselectivities by using squaramide catalysis. [ABSTRACT FROM AUTHOR]

The article presents chemical equations related to the article "Highly Enantioselective Construction of Tricyclic Derivatives by the Desymmetrization of Cyclohexadienones" by C. Martin-Santos and others, published in the periodical "Angewandte Chemie International Edition" in 2014.

Enantiopure trans-dihydroarylfurans (II), (V) and (VII) are synthesized from (Z)-bromonitroalkenes (II) and naphthol (I) or phenol derivatives (IV) and (VI), resp., in good yields and high enantioselectivity by using a squaramide catalyst. [ABSTRACT FROM AUTHOR]

A new organocatalytic synthesis of 3,4-disubstituted pyrroles is presented, involving the one-pot, two-step reaction of aldehydes, e.g. (I), with gem-bromonitroalkenes, e.g. (II), and amines, e.g. (III). [ABSTRACT FROM AUTHOR]

The selective double hydroboration of CO 2 into bis(boryl)acetal (BBA) is a challenging yet appealing reduction process since BBA can be used as a versatile C 1 and C n 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 CO 2 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 LiH 2 BBN catalyzed the hydroboration of CO 2 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 CO 2 .

GABA A receptors (GABA A Rs) are targets for important classes of clinical agents (e.g., anxiolytics, anticonvulsants, and general anesthetics) that act as positive allosteric modulators (PAMs). Previously, using photoreactive analogs of etomidate ([ 3 H]azietomidate) and mephobarbital [[ 3 H]1-methyl-5-allyl-5-( m -trifluoromethyl-diazirynylphenyl)barbituric acid ([ 3 H] R - m TFD-MPAB)], we identified two homologous but pharmacologically distinct classes of general anesthetic binding sites in the α 1 β 3 γ 2 GABA A R transmembrane domain at β + - α - ( β + sites) and α + - β - / γ + - β - ( β - sites) subunit interfaces. We now use competition photolabeling with [ 3 H]azietomidate and [ 3 H] R-m TFD-MPAB to identify para -substituted propofol analogs and other drugs that bind selectively to intersubunit anesthetic sites. Propofol and 4-chloro-propofol bind with 5-fold selectivity to β + , while derivatives with bulkier lipophilic substitutions [4-( tert -butyl)-propofol and 4-(hydroxyl(phenyl)methyl)-propofol] bind with ∼10-fold higher affinity to β - sites. Similar to R-m TFD-MPAB and propofol, these drugs bind in the presence of GABA with similar affinity to the α + - β - and γ + - β - sites. However, we discovered four compounds that bind with different affinities to the two β - interface sites. Two of these bind with higher affinity to one of the β - sites than to the β + sites. We deduce that 4-benzoyl-propofol binds with >100-fold higher affinity to the γ + - β - site than to the α + - β - or β + - α - sites, whereas loreclezole, an anticonvulsant, binds with 5- and 100-fold higher affinity to the α + - β - site than to the β + and γ + - β - sites. These studies provide a first identification of PAMs that bind selectively to a single intersubunit site in the GABA A R transmembrane domain, a property that may facilitate the development of subtype selective GABA A R PAMs., (Copyright © 2019 by The American Society for Pharmacology and Experimental Therapeutics.)

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.

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 precursors.