Synthesis of β-Carbonyl α-Iminoamides by Double Insertion of Isocyanides into Aldehydes

An unprecedented trimethylsilyl trifluoromethanesulfonate (TMSOTf)-promoted selective double insertion of isocyanides into aldehydes was developed, providing an efficient protocol for synthetically challenging β-carbonyl α-iminoamides. The given approach is applicable for a diverse selection of readily accessible aldehydes, along with isocyanides serving as essential precursors for "amide" and "imine" scaffolds. The versatile transformations of the given products were demonstrated, and the pivotal intermediates for the plausible mechanism were identified.

Discovery and structure-activity relationship of Morita-Baylis-Hillman adducts as larvicides against dengue mosquito vector, Aedes aegypti (Diptera: Culicidae)

Neglected tropical diseases (NTDs) have become a significant public health problem worldwide, notably the life-threatening dengue hemorrhagic fever borne by the Aedes aegypti mosquito. Thus, mosquito vector control measures remain essential in public health vector surveillance and control to combat Aedes-borne infections. Therefore, a series of MBH adducts were synthesized and assessed towards the fourth instar mosquito larvae, Aedes aegypti, along with the preliminary structure-activity relationship (SAR). Noteworthy, this compound class might be synthetized by an efficient eco-friendly synthesismethod and a rapid route for the synthesis of commercial larvicide through a single synthetic step. The bioassays showed that this compound class is a promising larvicide to control Aedes aegypti mosquito larvae, mainly 3g, with an LC₅₀ of 41.35 µg/mL, which was higher than evaluated positive controls. Nevertheless, it is a viable larvicidalhit candidate for further hit-to-leadproperties optimization of its biphenyl backbone scaffold with enhanced insecticidalbioactivity. Moreover, scanning electron microscopy analysis suggested a disruption of the osmoregulatory/ionoregulatory functions by the complete deterioration of the terminal exoskeleton hindgut and anal papillae. Therefore, this new study shows the larvicidal efficacy of the tested compounds against the Aedes aegypti larvae.

Acyl Transfer-Driven Rauhut-Currier Dimerization of Morita-Baylis-Hillman Ketones

A serendipitous Rauhut-Currier dimerization of 1,1-disubstituted activated olefins derived from Morita-Baylis-Hillman adducts was observed in the presence of DABCO. The reaction is driven by the migration of an acyl group and produces multifunctionalized enol esters in yields greater than 90% in most cases, without necessitating column chromatographic purification. The acyl transfer is thought to proceed via a transition state typical of a Morita-Baylis-Hillman (MBH) reaction, supported by a brief mechanistic study involving computational calculations.

Synthesis of 2,2-Disubstituted Dihydro-1,4-benzothiazines from Morita-Baylis-Hillman Ketones by an Oxidative Cyclization

An oxidative cyclization ensued upon interaction of Morita-Baylis-Hillman (MBH) ketones with 2-aminothiophenol in the presence of Cs₂CO₃, resulting in the formation of new 2,2-disubstituted dihydro-1,4-benzothiazines. The reaction features an aza-Michael addition and an oxidative cyclization involving the formation of a carbon-sulfur bond and works well over a wide range of MBH ketones to deliver the dihydrobenzothiazines in good yields in reasonable reaction times under mild conditions.

Diamine-mediated degradative dimerisation of Morita-Baylis-Hillman ketones

A degradative dimerisation of Morita-Baylis-Hillman ketones was observed in the presence of a primary diamine. The reaction proceeded swiftly to produce methylene-bridged 1,3-dicarbonyl compounds. A brief mechanistic investigation alluded to a retro-Mannich reaction as the key step of the transformation.

gem-Dichlorocyclopropanation of Dicarbonyl Derivatives

A novel methodology for the 1,1-dichlorocyclopropanation of dicarbonyl conjugated olefins was described. The developed protocol is simple and uses readily accessible starting materials, allowing the isolation of the desired adducts in moderate to excellent yields (up to 99 %). Furthermore, the reaction tolerated scale up to the gram scale; thus highlighting the synthetic potential of this transformation. Control experiments and DFT studies revealed that the reaction proceeded through a Michael-initiated ring-closure process, in which reaction temperature played a crucial role. Finally, these gem-dichlorocyclopropanes were also employed in the preparation of a trisubstituted naphthyl derivative and a diastereoselective reduction was also demonstrated.

Synthesis of 1 H-Pyrrol-3(2 H)-ones via Three-Component Reactions of 2,3-Diketo Esters, Amines, and Ketones

An efficient one-pot, three-component reaction of 2,3-diketo esters with amines and ketones has been developed for the synthesis of 1 H-pyrrol-3(2 H)-ones. By using trifluoroacetic acid (TFA) as the additive and acetonitrile (MeCN) as the solvent, this convenient method provides a library of 1 H-pyrrol-3(2 H)-ones in moderate to good yields. The simple protocol features readily available starting materials, a straightforward process, good functional group tolerance, and broad substrate scope.

Enantio- and Diastereoselective Organocatalytic Conjugate Additions of Nitroalkanes to Enone Diesters

Enantio- and diastereoselective conjugate addition reactions between nitroethane or nitropropane and enone diesters are reported. A bifunctional triaryliminophosphorane catalyzed the addition reaction with consistently excellent stereoselectivities and yields across a wide range of substrates. By the use of the gem-diester functional handle present in the adducts, local desymmetrization via diastereotopic group discrimination was demonstrated, and a polyfunctionalized lactam with three contiguous stereocenters was synthesized.

Aza-Riley Oxidation of Ugi-Azide and Ugi-3CR Products toward Vicinal Tricarbonyl Amides: Two-Step MCR-Oxidation Methodology Accessing Functionalized α,β-Diketoamides and α,β-Diketotetrazoles

Direct oxidative deamination of glyoxal-derived Ugi-azide and Ugi three-component reaction products readily affords vicinal tricarbonyls (α,β-diketoamides) and α,β-diketotetrazoles with two diversity elements. This significant extension of our previously described multicomponent reaction-oxidative deamination methodology is proposed to proceed through a mechanistically distinct SeO₂-mediated C-N oxidation derived from an active enol of α-amino-β-ketone systems, effectively an aza-Riley oxidation. This methodology accesses diverse VTC systems from prototypical amines, glyoxaldehydes, and isocyanide building blocks in a mere two steps.

Oxidation of β-Ketoamides: The Synthesis of Vicinal Tricarbonyl Amides

A facile and direct oxidative reaction for the synthesis of vicinal tricarbonyl amides in moderate to excellent yields (53-88%) was developed starting from readily available β-ketoamides in the presence of phenyliodine(III) bis(trifluoroacetate). The resulting products possess significant synthetic potential, making this approach a valuable addition to the group of traditional methods already available for the preparation of these molecules.

Hypervalent iodine catalysis for selective oxidation of Baylis–Hillman adducts via in situ generation of o-iodoxybenzoic acid (IBX) from 2-iodosobenzoic acid (IBA) in the presence of oxone

An efficient, eco-friendly protocol for selective oxidation of primary and secondary Baylis–Hillman alcohols to the corresponding carbonyl compounds in high yields has been developed with 2-iodosobenzoic acid (IBA).

Iodosobenzene-mediated direct and efficient oxidation of β-dicarbonyls to vicinal tricarbonyls catalyzed by iron(iii) salts

The direct and efficient oxidation of β-dicarbonyls to vicinal tricarbonyl compounds has been achieved, which was mediated by PhIO and catalyzed by Fe(NO₃)₃·9H₂O under mild and environmentally friendly conditions.