Morita Baylis Hillman Adducts Research Articles

Palladium‐Catalyzed Asymmetric Construction of Vicinal Tertiary and All‐Carbon Quaternary Stereocenters by Allylation of β‐Ketocarbonyls with Morita–Baylis–Hillman Adducts

AbstractPalladium‐catalyzed regio‐, diastereo‐, and enantioselective allylic alkylation of β‐ketocarbonyls with Morita–Baylis–Hillman adducts has been developed using a spiroketal‐based diphosphine (SKP) as the ligand, thus affording a range of densely functionalized products bearing vicinal tertiary and all‐carbon quaternary stereodyad in high selectivities. The utility of the protocol was demonstrated by the facile synthesis of some complex molecules by simple product transformations.

Palladium-Catalyzed Asymmetric Construction of Vicinal Tertiary and All-Carbon Quaternary Stereocenters by Allylation of β-Ketocarbonyls with Morita-Baylis-Hillman Adducts.

Palladium-catalyzed regio-, diastereo-, and enantioselective allylic alkylation of β-ketocarbonyls with Morita-Baylis-Hillman adducts has been developed using a spiroketal-based diphosphine (SKP) as the ligand, thus affording a range of densely functionalized products bearing vicinal tertiary and all-carbon quaternary stereodyad in high selectivities. The utility of the protocol was demonstrated by the facile synthesis of some complex molecules by simple product transformations.

Palladium-catalyzed nucleophilic allylic substitution of Morita–Baylis–Hillman adducts with enamines: Synthesis of 1,5-dicarbonyl compounds

An efficient nucleophilic allylic substitution of a variety of Morita–Baylis–Hillman adducts with enamines catalyzed by Pd(OAc) 2 in the presence of ZnBr 2 as a promoter is described in the present study. The reaction gives S N 2-type 1,5-dicarbonyl compounds that may subsequently undergo an intramolecular conjugate addition onto the enone moiety affording the corresponding 1,4-adducts. All the synthesized compounds have been isolated in moderate to good yields and fully characterized.

Synthesisof16NewHybridsfromTetrahydropyrans DerivativesandMorita-Baylis-HillmanAdducts:In VitroScreeningagainstLeishmaniadonovani.

Leishmaniases are a group of neglected tropical diseases (NTDs) caused by protozoan parasites from >20 Leishmania species. Visceral leishmaniasis (VL), also known as kala-aza, is the most severe form of leishmaniasis, usually fatal in the absence of treatment in 95% of cases. The Morita-Baylis-Hillman adducts (MBHAs) are being explored as drug candidates against several diseases, one of them being leishmaniasis. We present here the design, synthesis and in vitro screening against Leishmania donovani of sixteen new molecular hybrids from analgesic/anti-inflammatory tetrahydropyrans derivatives and Morita-Baylis-Hillman adducts. First, acrylates were synthesized from analgesic/anti-inflammatory tetrahydropyrans using acrylic acid under TsOH as a catalyst (70%–75% yields). After the 16 new MBHAs were prepared in moderate to good yields (60%–95%) promoted by microwave irradiation or low temperature (0 °C) in protic and aprotic medium. The hybrids were evaluated in vitro on the promastigote stage of Leishmania donovani by determining their inhibitory concentrations 50% (IC50), 50% hemolysis concentration (HC50), selectivity index (HC50/IC50,), and comparing to Amphotericin B, chosen as the anti-leishmanial reference drug. The hybrid which presents the bromine atom in its chemical structure presents high leishmanicide activity and the high selectivity index in red blood cells (SIrb > 180.19), compared with the highly-toxic reference drug (SIrb = 33.05), indicating that the bromine hybrid is a promising compound for further biological studies.

Methylsulfenylation of Electrophilic Carbon Atoms: Reaction Development, Scope, and Mechanism

An innovative method for the methylsulfenylation of electrophilic carbons was explored. Cheap and commercially available dimethyl sulfoxide (DMSO) was used as a source of the –SCH3 group. Chalcone, dibenzylideneacetone, and Morita–Baylis–Hillman adduct derivatives were successfully sulfenylated to give the corresponding products in moderate to high yields. Control experiments and DFT calculations revealed deoxygenation of DMSO and nucleophilic addition of a sulfur intermediate as key steps in the entire mechanism.

Control of Chemo-, Regio-, and Enantioselectivity in Copper Hydride Reductions of Morita-Baylis-Hillman Adducts.

Nonracemically ligated copper hydride can be used to effect tandem SN2'/1,2-reductions of racemic Morita-Baylis-Hillman (MBH) acetates to access enantioenriched chiral allylic alcohols with defined olefin geometry. MBH esters, including those with β-substitution, can be transformed to stereodefined enoates by taking advantage of a bulky, oligomeric, in situ generated trialkoxysiloxane leaving group. Finally, an atypical conversion of easily arrived at MBH alcohol derivatives to nonracemic allylic alcohols is disclosed.

Morita-Baylis-Hillman Adducts Display Anti-Inflammatory Effects by Modulating Inflammatory Mediator Expression in RAW264.7 Cells.

Inflammatory response plays an important role not only in the normal physiology but also in pathologies such as cancers. The Morita-Baylis-Hillman adducts (MBHA) are a novel group of synthetic molecules that have demonstrated many biological activities against some parasitic cells such as Plasmodium falciparum, Leishmania amazonensis, and Leishmania chagasi, and antimitotic activity against sea urchin embryonic cells was also related. However, little is known about the mechanisms induced by MBHA in inflammatory process and its relation with anticancer activity. The present work investigated the cytotoxicity of three MBHA derivatives (A2CN, A3CN, and A4CN), on human colorectal adenocarcinoma, HT-29 cells, and their anti-inflammatory activities were examined in lipopolysaccharide- (LPS-) stimulated RAW264.7 macrophage cells, being these derivatives potentially cytotoxic to HT-29 cells. Coincubation with A2CN, A3CN, or A4CN and LPS in RAW264.7 cells inhibited NO production, as well as the production of reactive oxygen species (ROS) was also repressed. The mRNA expressions of IL-1β and IL-6 were significantly downregulated by such MBHA compounds in RAW264.7 cells, but only A2CN was able to inhibit the COX-2 gene expression. We also showed that MBHA compounds decreased almost to zero the production of IL-1β and IL-6. These findings display that such MBHA compounds exhibit anticancer and anti-inflammatory activities.

Palladium-Catalyzed Asymmetric Allylic Allylation of Racemic Morita-Baylis-Hillman Adducts.

A palladium-catalyzed asymmetric allyl-allyl cross-coupling of acetates of racemic Morita-Baylis-Hillman adducts and allylB(pin) has been developed using a spiroketal-based bis(phosphine) as the chiral ligand, thus affording a series of chiral 1,5-dienes bearing a vinylic ester functionality in good yields, high branched regioselectivities, and uniformly excellent enantioselectivities (95-99 % ee). Further synthetic manipulations of the allylation products provided novel ways for rapid access to a range of chiral polycyclic lactones and polycyclic lactams, as well as the antidepressant drug (-)-Paroxetine, in high optical purities.

ChemInform Abstract: A Single‐Flask Synthesis of Morita—Baylis—Hillman Adducts from Ethoxyacetylene and Carbonyl Compounds: Synthesis of Subamolides D and E.

AbstractLithiation of ethoxyacetylene and sequential addition reaction with aldehydes and/or ketones and BF3·OEt2 leads to 2‐hydroxymethyl enoates in good to excellent overall yields.

A Facile Anti-selective Synthesis of 3-Nitropyridin-2-ones Using Morita- Baylis Hillman Adduct of Nitroalkene

Background: Amide functionality is an important in many areas of chemistry, including peptide, polymer, and complex molecule synthesis. Furthermore, Morita-Baylis-Hillman (MBH) reaction is well known efficient and economical carbon-carbon bond forming reaction which affords densely functionalized scaffolds. δ-Lactams are important constituents of natural products and have widespread applications from pharmaceuticals to synthetic organic chemistry. To the best of our knowledge, MBH adducts of nitro alkenes and their further oxidized products have not been utilized to construct the target molecule of present investigation. With aim to incorporate nitro group in pyridin-2-ones, we wished to prepare MBH adduct of nitroalkenes, which would be a novel scaffold that can be utilized for synthesis of diverse molecules. Methods: A flame-dried round bottom flask was charged with benzimidazolium salt, α- nitrocinnamaldehyde, phenacyl bromide, and amine in THF/ButOH under positive pressure of nitrogen followed by addition of DBU. The resulting pale yellow solution was stirred for 12-14 h at room temperature and finally after work-up we isolated the desired amide. Then, a mixture of prepared amide and molecular iodine in dichloromethane was stirred at room temperature for 4.5-6 h yields the target lactams. Results: [E]-α-Nitrocinnamaldehydes, prepared from Morita-Baylis-Hillman adduct of nitoalkenes, were converted into functionalized amides (81-95%) under the catalysis of N-heterocyclic carbenes. The reaction proceeds via d3 nucleophile of homoenolate and involves three components coupling strategy. A probe to utilized the prepared amide scaffold for construction of pyridin-2-one was also performed and the reactions gave excellent yields (82-93%) of pure products with highly diastereoselective (>92%) in favor of trans isomer. Conclusion: We have documented an original NHC-catalyzed direct synthesis of α-nitro amides with diverse functionalities, which opens up a new aspect for the utility of MBH adducts of nitroalkenes in organic synthesis. We have also disclosed a new anti-selective synthesis of 3-nitropyridin-2-ones from the prepared amide scaffold. Thus, the envisaged atom-economic strategy for the synthetically important functionalized amides and pharmaceutically important 2-pyridones would be a practical alternative to the existing procedures for their preparations. Keywords: Nitroalkene, Baylis-Hillman adduct, N-heterocyclic carbene, pyridin-2-one, stereoselectivity.

Synthesis and In Vitro Anti Leishmania amazonensis Biological Screening of Morita-Baylis-Hillman Adducts Prepared from Eugenol, Thymol and Carvacrol.

Leishmaniasis represents a series of severe neglected tropical diseases caused by protozoa of the genus Leishmania and is widely distributed around the world. Here, we present the syntheses of Morita-Baylis-Hillman adducts (MBHAs) prepared from eugenol, thymol and carvacrol, and their bioevaluation against promastigotes of Leishmania amazonensis. The new MBHAs are prepared in two steps from essential oils in moderate to good yields and present IC50 values in the range of 22.30–4.71 μM. Moreover, the selectivity index to the most potent compound is very high (SIrb > 84.92), far better than that of Glucantime® (SIrb 1.39) and amphotericin B (SIrb = 22.34). Conformational analysis were carried out at the M062X//6-31+G(d,p) level of theory to corroborate a hypothesis about the nitroaromatic bioreduction mechanism.

Bioreduction of α‐Acetoxymethyl Enones: Proposal for an SN2′ Mechanism Catalyzed by Enereductase

Abstract(Z)‐3‐Acetoxymethyl‐4‐R‐3‐buten‐2‐ones (R=aryl, alkyl) and (Z)‐3‐methyl‐4‐R‐3‐buten‐2‐ones (R=aryl) were synthesized and submitted to reduction by the yeast Saccharomyces cerevisiae producing the (R)‐ and (S)‐4‐R‐3‐methybutan‐2‐ones, respectively. This stereochemistry control strategy was applied in the syntheses of (R)‐ and (S)‐Tropional® with moderate to high enantiomeric excesses. Other (Z)‐3‐acyloxymethyl‐4‐phenyl‐3‐buten‐2‐ones showed similar behavior to the (Z)‐3‐acetoxymethyl counterpart, and the acylated Morita–Baylis–Hillman adduct 1‐acetoxy‐2‐methylene‐1‐phenylbutan‐3‐one produced a mixture of products, with and without the acetoxy group, via three different reaction pathways. In addition to experiments employing whole cells, those in which isolated enereductases were used suggested that the main pathway through which the loss of the acetoxy group occurs during the biocatalytic cascade is an SN2′‐type reaction, rather than formal hydrogen addition followed by acetic acid elimination. Finally, related ethyl enones were reduced enantioselectively by the yeast Candida albicans, producing both (R)‐ and (S)‐reduction products, depending on the presence of the acetoxy group in the starting material.magnified image

Morita-Baylis-Hillman (MBH) Reaction Derived Nitroallylic Alcohols, Acetates and Amines as Synthons in Organocatalysis and Heterocycle Synthesis.

The Morita-Baylis-Hillman (MBH) reaction is one of the most useful and efficient protocols for constructing new carbon-carbon bonds between an activated olefin and electrophiles in the presence of a tertiary amine/phosphine. Herein, we present the use of MBH alcohols, which are obtained from the reaction of nitrostyrenes with aldehydes, as well as acetates and amines derived thereof in several organocatalytic transformations. Densely functionalised MBH adducts can also be used to synthesise substituted heteroaromatic compounds, such as furan, pyrrole, pyrazole and imidazole derivatives.

Synthesis, Cytotoxic Activity on Leukemia Cell Lines and Quantitative Structure-Activity Relationships (QSAR) Studies of Morita-Baylis-Hillman Adducts

The Morita-Baylis-Hillman reaction is an organocatalyzed chemical transformation that allows access to small poly-functionalized molecules and has considerable synthetic potential and promising biological profiles. The Morita-Baylis-Hillman adducts (MBHA) are a new class of bioactive compounds and highlight its potentialities to the discovery of new cheaper and efficient drugs, e.g. as anti-Leishmania chagasi and Leishmania amazonensis, anti- Trypanosoma cruzi, anti-Plasmodium falciparum and Plasmodium berghei, lethal against Biomphalaria glabrata, antibacterial, antifungal, herbicide and others. The goal of this work is to describe the primary cytotoxic activities against strains of human leukemia HL-60 cell line for thirty-four Morita-Baylis- Hillman adducts (MBHA), followed by a Quantitative Structure-Activity Relationships study (QSAR). The conventional or microwave-assisted syntheses of MBHA, derived from substituted aromatics or Isatin, were performed in good to excellent yields (70-100%) in short reaction times, using protocols recently developed by us. Isatin derivatives, MBHA 31 and 32, were the most active in this congener series of compounds, with IC50 values of 10.8 μM and 7.8 μM, respectively. The primary cytotoxic activities against chronic leukemia cells (K562) were also evaluated to these two most active compounds (MBHA 31 and 32), presenting IC50 values of 53 μM and 43 μM respectively. QSAR study was performed considering 3D, 2D and constitutional molecular descriptors. These were selected from Ordered Predictor Selection algorithm and submitted to Partial Least Squares Modeling. We present an interesting investigation about cytotoxic activities on human leukemia cell line (HL-60) for 34 synthetic MBHA. In a good way we discovered that the most cytotoxic compounds (31-32, 10.8 μM and 7.8 μM respectively) were also prepared quantitatively (100% yields) in a short reaction time using microwave irradiation. We demonstrate that 31 and 32 induced apoptosis and not necrosis in HL-60 cells, observed by externalization of PS and increase Anexin-V positive cells. Quantitative Structure-Activity Relationships considering 3D, 2D and constitutional descriptors provided a robust and predictive PLS model, in accordance with SAR observations.

α-Functionalization of Nitroalkenes and Its Applications in Organic Synthesis

The applications of Morita–Baylis–Hillman (MBH) and Rauhut–Currier (RC) adducts of nitroalkenes in the synthesis of various carbo- and heterocycles are summarized in this review. In recent years, the MBH adducts and their derivatives such as acetates and bromides have served as efficient synthons for the synthesis of bioactive compounds including natural products. The close proximity of various functional groups makes the MBH and RC adducts extremely valuable substrates in multicomponent and cascade reactions, including annulations, organocatalysis, and kinetic resolution, to name a few.

ChemInform Abstract: An Efficient Synthesis of α‐Isothiocyanato‐α,β‐unsaturated Esters from Morita—Baylis—Hillman Adducts.

AbstractA facile one‐pot method for the synthesis of the title esters is developed involving the dehydration of the nitroalkane side‐chain of Morita—Baylis—Hillman adducts generating the corresponding nitrile oxide, and the following [3+2] cycloaddition to the C=S bond of thiourea affording a diaminooxathiazole intermediate.

ChemInform Abstract: An Efficient Synthesis of Dihydrobenzo[c]azepines from Morita—Baylis—Hillman Adducts via Pictet—Spengler Reaction.

Various dihydrobenzo[c]azepines were synthesized in good yields via Pictet–Spengler cyclization protocol from tosylamide derivatives of Morita–Baylis–Hillman adducts and 1,3,5-trioxane. The synthesis was carried out in the presence of easily removable montmorillonite K-10 in short time in high yields.

A Single-Flask Synthesis of Morita-Baylis-Hillman Adducts from Ethoxyacetylene and Carbonyl Compounds: Synthesis of Subamolides D and E.

Sequential treatment of (ethoxyethynyl)lithium with aldehydes and/or ketones (2 and 4) and BF3·OEt2 gives rise to β-hydroxyenoates 5 in good to excellent overall yields. Similarly, the combination of 1 (M = Li) and dicarbonyl compounds 6 (X = O) or keto/aldehyde acetals (X = OMe) followed by the addition of a Lewis acid leads to five-, six-, and seven-membered hydroxycycloalkene carboxyates. The utility of this method is demonstrated in the synthesis of the α-alkylidene lactone natural products subamolide D and E.

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.

ChemInform Abstract: Enantioselective Allylic Substitution of Morita—Baylis—Hillman Adducts Catalyzed by Chiral Bifunctional Ferrocenylphosphines.

AbstractAir‐stable chiral ferrocenylphosphines are synthesized and utilized in the asymmetric allylic substitution of Morita—Baylis—Hillman adducts with phthalimide under mild reaction conditions.