Eduardo González-Zamora

Multicomponent domino process to oxa-bridged polyheterocycles and pyrrolopyridines, structural diversity derived from work-up procedure

Novel three-component domino processes to polyheterocycles are developed. Reaction of an allylamine, an aldehyde and an alpha -isocyanoacetamide in methanol at room temp. provides an efficient access to an oxa-bridged tricycle as a single diastereoisomer. In this one-pot process, one C-N, one C-O and three C-C bonds are formed with concomitant creation of five asym. centers. While isolable, the oxa-bridged tricycles can be cleanly in-situ fragmented to pyrrolopyridines under acidic conditions (trifluoroacetic acid, -78 DegC), providing thus an unusual work-up derived structural diversity. The operational simplicity and excellent chem. yield make these novel heterocycle syntheses valuable in diversity-oriented high throughput synthesis. [on SciFinder (R)]

Sulfated Zirconia-Catalyzed Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones (DHPMs) Under Solventless Conditions: Competitive Multicomponent Biginelli vs. Hantzsch Reactions

The catalytic ability of ZrO(2)/SO(4)(2-) to promote solventless three-component condensation reactions of a diversity of aromatic aldehydes, urea or thoiurea and ethyl acetoacetate was studied. Products resulting from Hantzsch and/or Biginelli multi-component reactions are obtained in the presence of solid acid catalysts using the same reactants but different temperature conditions. The sulfated zirconia catalyst can be recovered and recycled in subsequent reactions with a gradual decrease of activity.

Catalytic activity of HKUST-1 in the oxidation of trans-ferulic acid to vanillin

HKUST-1 was used as a catalyst in the conversion of trans-ferulic acid to vanillin. The generation of unsaturated metal sites within HKUST-1 is the fundamental step in the catalytic process. When activated under vacuum, the catalyst gives complete conversion in only 1 h with a significant average reaction yield of 95%.

CO2 capture under humid conditions in metal–organic frameworks

Metal–organic frameworks (MOFs) are one of the most promising candidates for CO2 capture due to their sorption selectivity towards CO2. The optimisation of the physical–chemical interactions between MOFs and CO2 molecules is the key to further amplification of CO2 capture. An emerging technology for CO2 capture is the construction of hybrid adsorbent MOFs via confinement of water inside the pores. This review article describes the recent progress in this field. Indeed, the pre-adsorption of small quantities of water within the micropores of MOF materials (constructed with hydroxo functional groups, μ2-OH) provides a positive impact on the overall CO2 capture. We anticipate that the current review article can offer useful information on the significant developments made for the enhancement of CO2 capture by confining water (and other solvents) within the pores of MOFs, which is a very promising technology for real-world applications, where MOF materials could be capable of serving as next-generation CO2 capture systems.

CO2 capture under humid conditions in NH2-MIL-53(Al): the influence of the amine functional group

The hydrostable MIL-53(Al) and NH2-MIL-53(Al) CO2 capture properties were confirmed by kinetic uptake experiments, under different humidity conditions with maximum CO2 captures of approximately 6.0 wt% and 4.6 wt%, respectively, at 5% RH at 30 °C. In the case of MIL-53(Al) this corresponds to a 1.7-fold increase (CO2 capture) in comparison to anhydrous conditions. NH2-MIL-53(Al) exhibited a considerably stronger affinity to water than MIL-53(Al), and its ability to capture CO2, under humid conditions, was significantly reduced. The in situ FTIR experiments show how the hydrophobicity of the pores within MIL-53(Al) enhanced and sustained the CO2 adsorption capabilities of the material under more realistic CO2 capture conditions.

Water adsorption properties of a Sc(III) porous coordination polymer for CO2 capture applications

Water adsorption at room temperature in NOTT-400 was investigated along with its ability to perform CO2 capture under relative humidity (RH) conditions. Thus, the CO2 capture was increased from 4.2 wt% (anhydrous conditions) to 10.2 wt% at 20% RH and 30 °C.

Water Adsorption Properties of NOTT-401 and CO2 Capture under Humid Conditions

The water-stable material NOTT-401 was investigated for CO2 capture under humid conditions. Water adsorption properties of NOTT-401 were studied, and their correlation with CO2 sequestration at different relative humidities (RHs) showed that the CO2 capture increased from 1.2 wt % (anhydrous conditions) to 3.9 wt % under 5% RH at 30 °C, representing a 3.2-fold improvement.

Carbon dioxide capture in the presence of water vapour in InOF-1

Kinetic uptake experiments on InOF-1 confirm a maximum of 5.42 wt% CO2 capture at 30 °C and a significant 2-fold increase (∼11 wt%) in CO2 capture under 20% relative humidity of water vapour. InOF-1 captures CO2 under humid conditions (10% and 20% RH) and at relatively high temperatures (40 and 50 °C) without any degradation of the crystalline structure which was corroborated by PXRD.

Sulphated Zirconia as an Eco-Friendly Catalyst in Acylal Preparation under Solvent-Free Conditions, Acylal Deprotection Assisted by Microwaves, and the Synthesis of Anhydro-Dimers of o-Hydroxybenzaldehydes

A solvent-free approach is described for the regioselective synthesis of acylals (1,1-diacetates) in shorter reaction times and higher yields, compared to conventional methodology using solvents. In the protection reaction of the o-hydroxybenzaldehyde the formation of acetyl compounds and anhydro-dimers was observed. The deprotection reaction involves microwave (MW) exposure of diluted reactants in the presence of solid sulphated zirconia (SZ) catalyst that can be easily recovered and reused. The sulphated zirconia was recycled several times without any loss of activity.

Lithium bromide-promoted three-component synthesis of oxa-bridged tetracyclic tetrahydroisoquinolines

Heating a toluene soln. of an alpha -(isocyano)acetamide deriv., an aldehyde and a 3-(2-aminophenyl)propenoic acid (aniline) deriv. in the presence of lithium bromide at 60 Deg provides an oxa-bridged tetracyclic tetrahydroquinoline in good to excellent yield as a mixt. of two separable diastereoisomers. In this one-pot multicomponent reaction, one C-N, one C-O and three C-C bonds are formed with concomitant creation of five asym. centers and three heterocycles. Fragmentation of epoxy-tetrahydroquinoline an under mild acidic conditions affords a 4,6-phenanthroline deriv. The multicomponent reaction of 2-isocyano-1-(4-morpholinyl)-3-phenyl-1-propanone with heptanal and 3-(2-aminophenyl)-2-propenoic acid Me ester gave (1R,2S,4aS,5S,10bS)-rel-5-hexyl-1,5,6,10b-tetrahydro-2-(4-morpholinyl)-3-(phenylmethyl)-2H-2,4a-epoxybenzo[f][1,7]naphthyridine-1-carboxylic acid Me ester (major product). [on SciFinder (R)]