Baylis Hillman Reaction Research Articles

ChemInform Abstract: Enantioselective Synthesis of Isoquinolines: Merging Chiral‐Phosphine and Gold Catalysis.

AbstractThis highly enantioselective synthesis of dihydroisoquinoline derivatives from aromatic sulfonated imines tethered with an alkyne moiety, through a one‐pot asymmetric relay catalysis of chiral‐phosphine and gold catalysts, is based on an asymmetric aza‐Morita—Baylis—Hillman reaction.

ChemInform Abstract: Morita—Baylis—Hillman Reaction of α,β‐Unsaturated Ketones with Allylic Acetates by the Combination of Transition‐Metal Catalysis and Organomediation.

An intermolecular Morita–Baylis–Hillman (MBH) reaction of α,β-unsaturated ketones with allylic acetates under the catalysis of 10 mol % of tetrakis(triphenylphosphine)palladium(0) and mediation of tributylphosphine has been developed in the presence of acetic acid, affording the desired α-coupling products. The MBH reaction has the advantages of good tolerance to many functional groups, excellent regioselectivity and E-stereoselectivity, and moderate to good yields.

ChemInform Abstract: Synthesis of Aryl‐(E)‐2‐(azidomethyl)alkenoate and Aryl‐(Z)‐2‐(azidomethyl)acrylonitrile from Aryl Aldehydes and Activated Alkenes via One‐Pot Way.

AbstractThe title compounds are prepared by a three‐step one‐pot process involving a Baylis—Hillman reaction of aryl aldehydes and activated alkenes followed by acetylation using acetic anhydride and nucleophilic substitution using sodium azide.

Mechanistically Inspired Route toward Hexahydro-2H-chromenes via Consecutive [4 + 2] Cycloadditions.

Utilizing two robust C-C bond-forming reactions, the Baylis-Hillman reaction and the Diels-Alder reaction, we report a highly enantio-, regio-, and diastereoselective synthesis of hexahydro-2H-chromenes via two sequential [4 + 2] cycloadditions. These tandem and formal cycloadditions have also been performed as a "one-pot" sequence to access the corresponding heterocycles constituting up to five contiguous stereocenters in excellent yields and stereoselectivity.

ChemInform Abstract: A Mild and Efficient Approach to Enantioenriched α‐Hydroxyethyl α,β‐Unsaturated δ‐Lactams.

AbstractThe preparation of a potentially versatile α‐substituted α,β‐unsaturated lactam is described.

Synthesis and activity of novel homodimers of Morita–Baylis–Hillman adducts against Leishmania donovani: A twin drug approach

It is reported here the synthesis of novel Homodimers 12–19 of Morita–Baylis–Hillman adducts (MBHA) from one-pot Morita–Baylis–Hillman Reaction (MBHR) between aromatic aldehydes as eletrophiles and ethylene glycol diacrylate as Michael acceptor (35–94% yields) using cheap and green conditions. The bioactivities were evaluated against promastigote form of Leishmania donovani. All homodimers showed to be more potent than corresponding monomers. It is worth highlighting that the halogenated homodimers 17 and 18 (0.50μM) is almost 400 times more active than the corresponding monomer 10 and 1.24 times more potent than the second-line drug amphotericin B (0.62μM). Moreover, the selectivity index to 18 is very high (SIrb>400) far better than amphotericin B (SIrb=18.73). This is the first report of twin drugs strategy applied on Morita–Baylis–Hillman adducts.

Triphenylphosphine Photorelease and Induction of Catalytic Activity from Ruthenium-Arene Complexes Bearing a Photoswitchable o-Tosylamide Azobenzene Ligand

The reactivity of cationic arene ruthenium complexes bearing a photoswitchable o-tosylamide azobenzene ligand toward various phosphorus nucleophiles was investigated. The resulting phosphine-ruthenium complexes containing an azobenzene ligand were isolated as the Z isomer. Under appropriate reaction conditions, quantitative triphenylphosphine photorelease from the complex was achieved through Z → E isomerization of the ligand. This process was applied to the photoinitiation of the catalytic aza-Morita–Baylis–Hillman reaction.

DFT exploration of mechanistic pathways of an aza-Morita–Baylis–Hillman reaction

A new bimolecular pathway for a model aza-MBH reaction is presented and then explored in more details by DFT/M06-2X calculations. For this bimolecular pathway, explicit formic acid was considered in the rate-determining step showing the beneficial action from this additive, which plays a role as a co-catalyst. According to the current computations, this mechanistic cycle is a feasible pathway for the formation of the aza adduct and it explains the experimental detection of a key intermediate. A comparative analysis of the current results and previous ones reveals the substrate and medium dependence of the aza-MBH reaction. These factors lead to distinct pathways for the reaction, uncovering the complexity for conducting this reaction.

A Porous Cu(II)-MOF with Proline Embellished Cavity: Cooperative Catalysis for the Baylis-Hillman Reaction.

l-Proline has been covalently attached in a rigid linear ligand, H4L, having an isophthalate moiety at each terminal to form the chiral ligand, H4LPRO. This linker has been used for the construction of a porous MOF, LCuPRO. The free l-proline moiety in the cavity of the framework in the presence of imidazole as a cocatalyst functions synergistically to catalyze the Baylis-Hillman reaction between α,β-unsaturated carbonyl compounds and aromatic aldehydes. High porosity of the framework is proven by the nitrogen adsorption isotherm.

ChemInform Abstract: Chiral N‐Phosphonyl Imines for an Aza‐Morita—Baylis—Hillman Reaction via Group‐Assisted Purification (GAP) Chemistry.

AbstractUtilization of group‐assisted purification chemistry provides pure products by washing the crude materials with hexane/ethyl acetate co‐solvents.

Enantioselective Organocatalytic Intramolecular Morita–Baylis–Hillman Reaction of Some Unusual Substrates

The hypothesis and rationale behind our recent contribution towards the development of an enantioselective organocatalytic intramolecular Morita–Baylis–Hillman (IMBH) reaction, leading to the synthesis of an array of cyclopentannulated arenes and heteroarenes, is discussed. The latest advancement has addressed some of the shortcomings of the MBH reaction. In addition, it is believed that this study paves the way for the consideration of new possibilities in MBH chemistry.

Novel securinine derivatives as topoisomerase I based antitumor agents

DNA topoisomerase I (Topo I) has been validated as a target for anticancer agents. In this study, a series of novel securinine derivatives bearing β′-hydroxy-α,β-unsaturated ketone moiety were designed and synthesized via a Baylis-Hillman reaction for screening as Topo I inhibitors and antitumor agents. Their topoisomerase I inhibitory activity as well as their cytotoxicity against four human cancer cell lines (A549, HeLa, HepG2, SH-SY5Y) were evaluated, and two pairs of diastereomers 4a-1 and 4a-6 with significant Topo I inhibitory activity and potent anti-proliferative activity against cancer cell lines were identified. The diastereomers were separated, and absolute configurations of five pairs of diastereomers were identified based on X-ray crystallographic analysis and circular dichroism (CD) spectra analysis. Further mechanism studies of the most active compounds 4a-1-R and 4a-1-S indicated that this kind of securinine derivative exhibits a different inhibitory mechanism from that of camptothecin, an established Topo I inhibitor. Unlike camptothecin, compounds 4a-1-R and 4a-1-S specifically inhibits the combination of Topo I and DNA rather than forming the drug-enzyme-DNA covalent ternary complex. In addition, molecular docking and molecular dynamic studies revealed the binding patterns of these compounds with Topo I.

ChemInform Abstract: Catalyst‐Controlled Regiodivergent Vinylogous aza‐Morita—Baylis—Hillman Reactions.

AbstractRegiodivergent vinylogous aza‐MBH reaction is developed.

Enantioselective Morita–Baylis–Hillman Reaction of Acrylates with Nitrobenzaldehydes Promoted by the Bifunctional Ferrocene-Based Phosphinothiourea Organocatalysts

A series of ferrocene-based bifunctional phosphinothiourea organocatalysts were synthesized and applied to the enantioselective Morita–Baylis–Hillman reaction of acrylates with nitrobenzaldehydes, giving the desired products in up to 99.7 % ee. The strong electron-withdrawing effect of nitro group and hydrogen bonding interactions between the thiourea moiety of catalyst and aldehyde might be crucial during the enantio-controlling process.

Morita-Baylis-Hillman Reaction of α,β-Unsaturated Ketones with Allylic Acetates by the Combination of Transition-Metal Catalysis and Organomediation.

An intermolecular Morita-Baylis-Hillman (MBH) reaction of α,β-unsaturated ketones with allylic acetates under the catalysis of 10 mol % of tetrakis(triphenylphosphine)palladium(0) and mediation of tributylphosphine has been developed in the presence of acetic acid, affording the desired α-coupling products. The MBH reaction has the advantages of good tolerance to many functional groups, excellent regioselectivity and E-stereoselectivity, and moderate to good yields.

ChemInform Abstract: Morita—Baylis—Hillman Reaction of β,β‐Disubstituted Enones: An Enantioselective Organocatalytic Approach for the Synthesis of Cyclopenta[b]annulated Arenes and Heteroarenes.

The first enantioselective organocatalytic intramolecular Morita-Baylis-Hillman (MBH) reaction of sterically highly demanding β,β-disubstituted enones is presented. The MBH reaction of β,β-disubstituted-α,β-unsaturated electron-withdrawing systems was previously considered to be unfeasible. Towards this end, designer substrates, which under simple and practical reaction conditions generate a variety of cyclopenta[b]annulated arenes and heteroarenes in excellent enantiopurities and near-quantitative yields in remarkably short reaction times, are described. The reason for the unusually facile nature of this reaction is attributed to the synergy guided and entropically favored intramolecular reaction. Further, this strategy provides easy access to a substantial number of bioactive natural products and pharmaceutically significant compounds.

Synthetic studies on Stemona alkaloids. Construction of the sessilifoliamides B and C and 1,12-secostenine skeleton

An original synthetic approach to the Stemona alkaloids stenine and sessilifoliamides B and C has been explored. The strategy relies on the early construction of the pyrroloazepine core (rings A and B) and latter addition of the furanone (ring D) and ethyl chain at C-10, which are the common structural features of the three alkaloids. The formation of the azabicyclic nucleus through an intramolecular Morita–Baylis–Hillman reaction of a properly substituted pyrrolidone has been extensively investigated by modifications on the substrate and all the parameters involved in the process and an efficient protocol in terms of yield and stereoselectivity has been developed. Despite many alternative tactics were explored, insurmountable difficulties found in the last synthetic steps have frustrated the completion of the syntheses. However, along the way, a plethora of new compounds was prepared, some of them containing the full skeleton of the targeted alkaloids, which can be useful for future synthetic applications.

Catalytic Efficiency of Primary β‐Amino Alcohols and Their Derivatives in Organocatalysis

Chiral primary β‐amino alcohols, constuting adjacently positioned Brønsted base and Brønsted acid sites, are emerging as very valuable bifunctional organocatalysts in a wide array of asymmetric organic transformations. Primary β‐amino alcohols represent inexpensive alternatives to other primary amino organocatalysts such as chiral diamines and cinchona‐alkaloid‐derived primary amines, being easy to synthesize and air‐stable and offering the potential for introduction of different functional groups and also for alteration of steric sites. Here we reveal the catalytic use of simple primary β‐amino alcohols and their derivatives as organocatalysts in Diels–Alder cycloaddition, aldol condensation, Michael addition, 1,3‐dipolar cycloaddition, the Morita–Baylis–Hillman reaction, cascade cyclization, allylation of isatins, Friedel–Crafts alkylation and epoxidation of olefins.

A mild and efficient approach to enantioenriched α-hydroxyethyl α,β-unsaturated δ-lactams

A straightforward approach toward enantioenriched α-substituted α,β-unsaturated δ-lactams is described. Although a considerable number of approaches toward α,β-unsaturated δ-lactams have been reported, there are relatively few examples of enantioenriched α,δ-disubstituted α,β-unsaturated δ-lactams formation. The δ-stereocenter was formed by addition of allylmagnesium bromide to an N-tert-butylsulfinyl imine. The α,β-unsaturated δ-lactam was furnished by ring-closing metathesis. Although Baylis–Hillman chemistry failed on this cyclic compound, introduction of the hydroxyethyl group prior to ring-closing metathesis was successful. A Baylis–Hillman reaction was used to introduce the substituent at the α-position of the α,β-unsaturated lactam.

ChemInform Abstract: Titanium Enolate Chemistry at the Beginning of the 21st Century

AbstractReview: [recent developments in the field of titanium(IV)‐mediated aldol, aldol‐like, Mannich, and Michael reactions, radical alkylation, oxidative couplings, and Morita—Baylis—Hillman reactions with special emphasis on the last fifteen years; 146 refs.