Discovery of an in situ carbocationic system using trityl chloride as a homogeneous organocatalyst for the solvent-free condensation of β-naphthol with aldehydes and amides/thioamides/alkyl carbamates in neutral media

Multicomponent synthesis of pyrimido[4,5-b] quinolines over a carbocationic catalytic system

Trityl chloride (TrCl) was efficiently used as a neutral catalyst for the multicomponent cyclization reaction of an aldehyde with dimedone and 6-amino-1,3-dimethyluracil for the preparation of pyrimido[4,5-b] quinolines in chloroform under reflux condition.

Synthesis of Naphthoxazinones in a One-Pot Two-Step Manner by the Application of Propylphosphonic Anhydride (T3P®)

A sequential one-pot two-step protocol has been elaborated for the synthesis of naphthoxazinones from 2-naphthol, methyl carbamate, and aromatic aldehydes. First, a three-component reaction was optimized with the dehydrating additive propylphosphonic anhydride (T3P®), resulting in 1-carbamatoalkyl 2-naphthols in good to excellent yields. Following the successful multicomponent approach, intramolecular acylation was performed at high temperature, again with the contribution of T3P®, resulting in naphthoxazinone derivatives in moderate yields. These two steps were optimized together in one-pot as well, and the sequential rise in the requisite temperature eventuated the optimal procedure for the multistep cascade.

Trityl-Containing Alcohols-An Efficient Chirality Transmission Process from Inductor to the Stereodynamic Propeller and their Solid-State Structural Diversity

The cascade process of a dynamic chirality transmission from the permanent chirality center to the stereodynamic triphenylmethyl group has been studied for series of optically active trityl derivatives. The structural analysis, carried out with the use of complementary methods, enabled us to determine the mechanism of chirality transfer. The process of chirality transmission involves a set of weak but complementary electrostatic interactions. The induction of helicity in a trityl propeller is revealed by rising non-zero cotton effects in the area of trityl UV-absorption. The presence of an additional stereogenic center in close proximity to the trityl-containing stereogenic center significantly affects the sign and, to a lesser extent, magnitude of the respective cotton effects. Despite the bulkiness of the trityl, in the crystalline phase, the molecules under study strictly fill the space. In the crystal, molecules form aggregates stabilized by OH•••O hydrogen bonds. However, the presence of two trityl groups precludes formation of OH•••O hydrogen bonding. Additionally, the trityl group seems to be responsible for the formation of the solid solutions by e.g., racemates of trans- and cis-2-tritylcyclohexanol. Therefore, the trityl group acts as a supramolecular protective group, which in turn can be used in the crystal engineering.

Chiral Cocrystal Solid Solutions, Molecular Complexes, and Salts of N-Triphenylacetyl-l-Tyrosine and Diamines

The molecular recognition process and the ability to form multicomponent supramolecular systems have been investigated for the amide of triphenylacetic acid and l-tyrosine (N-triphenylacetyl-l-tyrosine, TrCOTyr). The presence of several supramolecular synthons within the same amide molecule allows the formation of various multicomponent crystals, where TrCOTyr serves as a chiral host. Isostructural crystals of solvates with methanol and ethanol and a series of binary crystalline molecular complexes with selected organic diamines (1,5-naphthyridine, quinoxaline, 4,4′-bipyridyl, and DABCO) were obtained. The structures of the crystals were planned based on non-covalent interactions (O–H···N or N–H⁺···O⁻ hydrogen bonds) present in a basic structural motif, which is a heterotrimeric building block consisting of two molecules of the host and one molecule of the guest. The complex of TrCOTyr with DABCO is an exception. The anionic dimers built off the TrCOTyr molecules form a supramolecular gutter, with trityl groups located on the edge and filled by DABCO cationic dimers. Whereas most of the racemic mixtures crystallize as racemic crystals or as conglomerates, the additional tests carried out for racemic N-triphenylacetyl-tyrosine (rac-TrCOTyr) showed that the compound crystallizes as a solid solution of enantiomers.

Dynamic optical activity induction in the N-alkyl-N'-trityl ureas and thioureas

Considered to be rigid, the urea and thiourea functionalities, often used in material chemistry and in asymmetric organocatalysis, are able to transmit information regarding 3D structure from a permanently chiral inducer part to a dynamically chiral (reporter) part of the molecule. Despite a considerable distance between the inducer and the reporter parts of the molecule, the chirality transfer phenomenon has been demonstrated for a series of secondary N-alkyl-N'-trityl ureas and thioureas. The induction of helicity in a stereodynamic trityl propeller is revealed by rising non-zero Cotton effects in the area of trityl absorption. The information regarding the 3D structure of the inducer is transferred to the reporter part of the system through a set of weak but complementary electrostatic interactions. The presence of two supramolecular motifs in the same molecule, characterized by opposite properties, significantly affected the molecular solid state structure of the thioureas and their abilities to assemble. In the crystalline phase, the model, a chiral N-tert-butyl-thiourea derivative that retains the extended Z,Z conformation of the linker, is prone to form a supramolecular network typical of secondary ureas and thioureas. In contrast, the presence of the hydrophobic trityl group suppresses the thioamide NHS[double bond, length as m-dash]C hydrogen bonds. Therefore, trityl acts as a supramolecular protecting group for thioamide functionality, hampering the formation of hydrogen bonded networks in the solid state.

Three-component condensation reaction of various aldehydes, dimedone and malononitrile catalyzed by boric acid in water in comparison with multifunctional ionic liquids as green catalytic systems

Triethanol ammonium acetate ([TEAH]+[OAc]−) and triethanol ammonium formate ([TEAH]+[HCOO]−) as multifunctional ionic liquids and catalysts were successfully applied for the preparation of tetrahydrobenzo[b]pyrans by the one-pot three-component condensation reaction of various aldehydes, dimedone and malononitrile under solvent-free conditions. These reactions were also tested using boric acid in water. In this catalytic system, by the reaction of water with boric acid, the hydronium ion caused by water separation can catalyze the reaction.

A highly effective and mild protocol for the production of 1-thioamidoalkyl-2-naphthols using 1,3-disulfonic acid imidazolium trifluoroacetate as a dual-functional catalyst

A solvent-free protocol for the production of 1-thioamidoalkyl-2-naphthols via a one-pot multi-component reaction of arylaldehydes with 2-naphthol and thioacetamide using the ionic liquid 1,3-disulfonic acid imidazolium trifluoroacetate ([Dsim][TFA]) is described. Furthermore, a plausible and attractive mechanism based on the dual functionality of the catalyst is proposed. Because of the dual functionality of [Dsim][TFA] (possessing acidic and basic sites), it is found to be generally highly effective, affording the products in high yields and short reaction times under mild conditions. We claim that this is one of the best protocols for the synthesis of 1-thioamidoalkyl-2-naphthols (in terms of yield, temperature, conditions, and/or the reaction time).

Antimony(III) Acetate an Efficient Catalyst for the Synthesis of 1-Amidoalkyl-2-Naphthols

Antimony(III) acetate was used in the one-pot three-component synthesis of multigram quantities of 1-amidoalkyl-2-naphthols from the condensation between aldehydes, 2-naphthol and acetamide under solvent-free conditions at ambient temperature. The present method has several advantages such as high yields, easy purification, mild reaction conditions, easy work-up, survival of different functional groups and very short reaction times.

Trityl chloride promoted the synthesis of 3-(2,6-diarylpyridin-4-yl)-1H-indoles and 2,4,6-triarylpyridines by in situ generation of trityl carbocation and anomeric based oxidation in neutral media

An efficient protocol for the synthesis of 2,4,6-triarylpyridines and 3-(2,6-diarylpyridin-4-yl)-1H-indoles by the one-pot pseudo four component condensation reaction of aldehydes with acetophenones and ammonium acetate in the presence of Ph3CCl under neutral and solvent-free conditions has been reported. Mechanistically, it is interesting that trityl chloride by in situ generation of trityl carbocation (Ph3C+) promotes the reaction. In this work, seven products have been reported for the first time.

Solvent-free preparation of amidoalkyl phenols catalyzed by trityl chloride under neutral media

A one-pot, multicomponent condensation reaction of phenols, aromatic aldehydes, and amides in the presence of catalytic amount of trityl chloride as a homogeneous organocatalyst under solvent-free condition to prepare amidoalkyl phenols has been reported. It is interesting that trityl chloride by in situ generation of trityl carbocation with inherent instability catalyzes the reaction.

Synthesis of 1,2,4,5-tetrasubstituted imidazoles using 2,6-dimethylpyridinium trinitromethanide {[2,6-DMPyH]C(NO2)3} as a novel nanostructured molten salt and green catalyst

2,6-Dimethylpyridinium trinitromethanide {[2,6-DMPyH]C(NO₂)₃} as a novel nanostructured molten salt catalyst (MS) was synthesized, characterized and used for the synthesis of 1,2,4,5-tetrasubstituted imidazoles under solvent-free conditions.

Magnetic core–shell titanium dioxide nanoparticles as an efficient catalyst for domino Knoevenagel–Michael-cyclocondensation reaction of malononitrile, various aldehydes and dimedone

Fe₃O₄@SiO₂@TiO₂ efficiently catalysed the preparation of tetrahydrobenzo[b]pyrans by a one-pot three component reaction of aldehydes, dimedone and malononitrile at 100 °C under solvent-free conditions.

Design of 1-methylimidazolium tricyanomethanide as the first nanostructured molten salt and its catalytic application in the condensation reaction of various aromatic aldehydes, amides and β-naphthol compared with tin dioxide nanoparticles

1-Methyl imidazolium tricyanomethanide {[HMIM]C(CN)₃} as a novel nano molten salt (MS) was synthesized and applied for the synthesis of 1-amidoalkyl-2-naphthols and compared with tin dioxide (SnO₂) nanoparticles.

N,2-Dibromo-6-chloro-3,4-dihydro-2H-benzo[e][1,2,4]thiadiazine-7-sulfonamide 1,1-dioxide: an efficient and homogeneous catalyst for one-pot synthesis of 4H-pyran, pyranopyrazole and pyrazolo[1,2-b]phthalazine derivatives under aqueous media

DCDBTSD was successfully applied in the synthesis of 4H-pyran, pyranopyrazole and pyrazolo[1,2-b]phthalazine derivatives by a one-pot multi-component reaction in water.

Choline peroxydisulfate oxidizing Bio-TSIL: triple role player in the one-pot synthesis of Betti bases and gem-bisamides from aryl alcohols under solvent-free conditions

The sequential one-pot multicomponent synthesis of Betti bases and bisamides using biodegradable choline persulfate.

Double helicity induction in chiral bis(triphenylacetamides)

Helicity induction in a highly flexible trityl chromophore is not only due to the presence of the neighboring stereogenic center(s).

Magnetically retrievable magnetite (Fe3O4) immobilized ionic liquid: an efficient catalyst for the preparation of 1-carbamatoalkyl-2-naphthols

An efficient and greener protocol for the synthesis of 1-carbamatoalkyl-2-naphthols using magnetically retrievable ionic liquid.