SIRT6, a crucial regulator of aging and cellular homeostasis, represents a promising target for small-molecule activation. In this study, we investigate griseofulvin and its derivatives as novel SIRT6 activators, focusing on the recently developed compound forvisirvat, which has progressed to Phase 2 clinical study. Biochemical evaluation revealed that griseofulvin itself possesses strong SIRT6-activating properties, achieving up to 10-fold activity at 100 μM. Modification of the griseofulvin scaffold generally led to reduced activity, prompting a focus on the oxadiazole moiety of forvisirvat. This strategy produced several analogues with higher potency, the most active at 100 μM being para-1,3,4-oxadiazolephenyl analog 21, which achieved 30-fold SIRT6 activation. Compounds bearing para-substituted phenyl rings exhibited excellent retention of activity at lower concentrations, with para-tolyl derivative 24 being the most potent at 10 μM. Retention of activity at pharmacologically relevant concentrations underscores their potential as potent SIRT6 activators and provides a rationale for continued development as drug candidates.

An alkene-tethered enaminone 7 was synthesized in four steps from bromoacetic acid and 3,3-dimethylallyl alcohol. The enaminone was fully characterized, including UV-Vis spectra. TBADT-catalyzed HAT of the alkene-tethered enaminone initiated a fragmentation that yielded the literature-known phenylacetone-derived enaminone.

Maleimides and their derivatives are highly versatile scaffolds with broad applications in synthetic chemistry, medicinal chemistry, and materials science; however, methods to expand their structural diversity remain limited. Here, we present a so far undescribed, metal-free, and mild strategy for the rapid construction of functionalized maleimides from readily available dihalomaleimide derivatives. The reaction is initiated by tertiary amine-mediated formation of an ammonium cation, which directs heteroannulation to efficiently generate heterobicyclic scaffolds. This modular approach also enables the synthesis of 3,4-diamino-substituted maleimides, including challenging second halogen substitutions with weak nucleophiles. Mechanistic studies indicate that a quaternary enamine intermediate plays a central role in steering the transformation, providing broad functional group tolerance and synthetically useful yields. Overall, this strategy offers a versatile platform for accessing structurally diverse maleimides, unlocking new opportunities in bioconjugation, medicinal chemistry, and materials science.

Amino acid derivatives, such as β-keto esters and pyrrolones, were used as nucleophiles in organocatalyzed Michael additions to nitroalkene acceptors, while fatty acid derivatives acted as both nucleophiles (β-keto esters) and electrophiles (nitroalkene acceptors). Bifunctional noncovalent organocatalysts were employed as asymmetric organocatalysts. Twenty compounds—including fatty acid and amino acid derivatives, as well as fatty acid–amino acid conjugates—were prepared with enantioselectivities of up to 98% ee. All novel products were fully characterized. This research demonstrates the ease of assembling readily available fatty acid and amino acid building blocks under ambient conditions.

LiAlH4 reduction of tert-butyl (S)-butyl(1-((2-cycloheptylethyl)amino)-1-oxo-3-phenylpropan-2-yl)carbamate (1) gave imidazolidine 2, while treatment with lithium diisopropylamide furnished the β-elimination product, cinnamamide 3. Both products were fully characterized. Reductive cyclization of N-alkylated-N-Boc-protected amino acid amides with LiAlH4 may be a viable synthetic method for trisubstituted chiral imidazolidines.

A series of cis-5-arylmethyl-2-alkyl-3-methylimidazolidin-4-ones, prepared from arylmethyl-substituted α-amino acids, and a series of trans- and cis-2-(fluoromethyl)-2,3-dimethylimidazolidin-4-ones, derived from L-valine and L-leucine, were synthesized and fully characterized. Their catalytic activity was evaluated in the addition of 1-methylindole to cinnamaldehyde. Using the cis-5-arylmethyl-2-alkyl-3-methylimidazolidin-4-one catalysts, enantioselectivities of up to 78% ee (S) were achieved. Notably, with the L-valine-derived cis-imidazolidinone organocatalyst, the highest reversal of stereoselectivity to date (92% ee, (R) at –43°C) was observed.

We report a one-pot, three-component synthesis of pyrazolo[1,2-a]pyridazinones from tetrahydropyridazines, a transformation that was historically challenging due to competing ring contractions. The resulting compounds undergo photoinduced transformations, without the need for external photocatalysts, to afford diverse 3D-rich derivatives, including tricyclic cyclobutenes and γ-(pyrazol-1-yl)butanals. Enabled by mild conditions, this strategy offers an efficient, atom-economical route to structurally diverse pyrazolo[1,2-a]pyridazinones and their derivatives.

Copper-catalyzed cycloadditions of terminal alkynes to 3-azido-4H-pyrido[1,2-a]pyrimidin-4-one and 3-azido-1-cyano-4H-quinolizin-4-one, prepared in four steps from methyl 2-benzoylamino-3-(dimethylamino)propenoate, yielded the corresponding 3-(1H-1,2,3-triazol-1-yl)-substituted 4H-pyrido[1,2-a]pyrimidin-4-ones and 4H-quinolizin-4-ones in 44-90 % isolated yields. The structures of the cycloadducts were determined by H-1 NMR, C-13 NMR, and 2D NMR techniques (COSY, HSQC, HMBC). The optical properties of the luminescent intermediates and final products were determined. In methanol, the compounds showed absorption at 350-400 nm, emission at 411-526 nm, and quantum yields of similar to 5 x 10(-2). Optical properties depended on the heterocyclic core (pyrido[1,2-a]pyrimidinone or quinolizinone), while the effect of substituents on optical properties was weak.

Two pyrazole derivatives were prepared in three steps from (camphor-3-yl)acetic acid. The pyrazole derivatives were fully characterized. The stereochemistry at the newly formed stereogenic center was confirmed by NOESY measurements and single crystal X-ray analysis.

Photocatalytic sulfanylations of (aza)quinolizine diazonium salts with disulfides and thiols, including N-Boc-protected cysteine and cystine esters, gave the corresponding fluorescent sulfanylation products in 25-85 % yield. Photocatalytic cycle was proposed for the sulfanylation with disulfides using diazonium salts as heteroaryl radical sources. Two representative diazonium salts were evaluated as bioconjugation reagents for fluorescent labeling of proteins using bovine serum albumin (BSA) as a model protein and targeting cysteine residues, and the results showed their applicability in fluorescent labeling under photocatalytic conditions.

Atom transfer radical addition (ATRA) reactions are essential transformations in organic synthetic chemistry that enable the atom-economic difunctionalization of abundant olefin feedstocks. In this way, a rich chemical space can be opened up by well-planned combinations of simple starting materials. To build an efficient photocatalytic transformation, the reactivity of trichloromethanesulfenyl chloride toward alkenes and alkynes was investigated under photocatalytic Cu(I) reaction conditions. In this study, we found that trichloromethanesulfenyl chloride can be added to a series of olefins (such as styrenes and electron-rich and -poor olefins) in the presence of 1 mol% [Cu(dmp)2]BF4 photocatalyst and blue LED irradiation, producing α-chloro trichloromethylthioethers in good yields. Experimental and theoretical (DFT) mechanistic studies are consistent with the proposed radical chain mechanism of transformation. This study may serve as a valuable reference for the development of new coupling reactions that are economical and highly efficient processes.

A series of azide- and cyclooctyne-functionalized N-hydroxysuccinimidyl esters (NHS esters) and benzotriazolides were prepared and used as N-acylation reagents to obtain azide-(BSA-1) and cyclooctyne-functionalized bovine serum albumin proteins (BSA-2), fluorescein derivatives 5 and 6, and homobifunctional linkers 3 and 4. Strain-promoted azide-alkyne cycloaddition (SPAAC) and copper-catalyzed azide-alkyne cycloaddition (CuAAC) of azide-functionalized fluorescent probe 5 and alkyne-functionalized fluorescent probe 6 with complementary functionalized proteins BSA-2 and BSA-1 yielded fluorescent cycloadducts BSA-2-5 and BSA-1-6. These cycloadducts were used to determine the loading of BSA-1 and BSA-2 with the respective azido and cyclooctyne groups based on their molar absorbances and fluorescence intensities. Dimerization through covalent cross-linking of BSA was then performed by SPAAC between azide-functionalized BSA-1 and cyclooctyne-functionalized BSA-2, and by treating BSA-1 and BSA-2 with 0.5 equiv. of complementary bis-cyclooctyne linker 4 and bis-azide linker 3. Although the formation of covalent dimers BSA-1-2-BSA, BSA-1-6-1-BSA, and BSA-2-5-2-BSA was detected by SDS-PAGE analysis, this was a minor process, and most of the functionalized BSA did not form covalent dimers.

(+)-Isocampholenic acid, prepared in two steps from (1S)-(+)-10-camphorsulfonic acid in 60% yield (on a scale of 172 mmol), served as the starting compound for the synthesis of small libraries of isocampholenic acid derivatives, comprising a total of 60 compounds, which are of interest due to their olfactory properties. Although isocampholenic acid derivatives are thermodynamically up to 5.9 kcal/mol less stable than endocyclic alkene isomers according to DFT calculation, only minor (up to 2%) isomerization to α-campholenic acid isomers was observed in most cases. The products were fully characterized, and their odor properties were preliminarily assessed by untrained laypersons. This study represents the first systematic exploration of the chemical space of isocampholenic acid. Novel derivatives with distinct odor profiles were discovered, and promising directions for future functionalization for fragrance development were identified.

A series of differently substituted β-enaminones 2a,b, 4a–i, 8a–d, and 9–13, their BF2-β-ketoiminate complexes 5a–d, and BF2-β-diketonate complexes 6a–d were prepared as model substrates for photochemical transformations. The attempted photochemical transformations of enaminones 2, 4, 8 and BF2-β-ketoiminate complexes 5 failed. On the other hand, irradiation of mixtures of BF2-β-diketonate complexes 6a–d and cycloalkanes with UV-A light (365 nm) gave the corresponding De Mayo reaction products 7a–f in 9–30% yields. The photochemical ring-expansion of acetyl tetralone-derived BF2-complex 6d gave novel diannulated cyclooctane derivatives 7e and 7f, which would be difficult to obtain using conventional cyclization methods.

A four-step synthesis process of bifunctional, noncovalent organocatalysts based on the chiral (1R,2R)-cyclohexane-1,2-diamine scaffold containing a 1,2-benzenediamine H-bond donor was developed. Nucleophilic aromatic substitution of the 2-fluoronitrobenzene derivative with the commercial (1R,2R)-cyclohexane-1,2-diamine was followed by selective alkylation of the primary amino group, reduction of the aromatic nitro group and final derivatization of the primary aromatic amino group, i.e., acylation, sulfonation, reductive alkylation and arylation, leading to the four subtypes of organocatalysts. All new compounds were fully characterized. The prepared organocatalysts (32 examples) were tested in the Michael addition of acetylacetone to trans-β-nitrostyrene, yielding the addition product with incomplete conversions (up to 93%) and enantioselectivities of up to 41% ee.

Four bifunctional, noncovalent amine-squaramide organocatalysts were prepared from camphor in five steps. The stereochemistry of the prepared catalysts was thoroughly analyzed using various spectroscopic techniques. Their organocatalytic activity was investigated in the Michael addition of acetylacetone to trans-β-nitrostyrene. The addition product was formed in complete conversion and with an enantioselectivity of up to 77% ee. In the reactions catalyzed by the 2-exo-3-endo catalysts, the major (S)-enantiomer was formed, whereas in the presence of 2-endo-3-endo catalysts, the (R)-enantiomer was formed as the major product.

In the search for novel polymeric molecules that could be used as electroactive materials, seven novel polyenaminones were prepared in high yields by the transaminative polymerization of resorcinol-derived bis-enaminones with m- and p-phenylenediamine and with 2,5-diaminohydroquinone. The obtained polymers show very low solubility in organic solvents and absorb UV light and visible light at wavelengths below 500 nm. All the obtained polymeric products were tested for redox activity in a Li battery setup. The 2,5-diaminohydroquinone-derived compound showed the best redox activity, with a maximum capacity of 86 mAh/g and relatively good capacity retention, thus confirming the hydroquinone group as the primary redox-active group. Other potential redox-active groups, such as resorcinol and conjugated carbonyls, showed limited activity, while variations in the phenylene groups and the substitution of phenolic groups in the resorcinol residue did not impact the electrochemical activity of the polymers. Their electrochemical properties, together with their previously established chemical recyclability, make polyenaminones promising scaffolds for the development of materials for sustainable energy storage applications.

Sulfonyl chlorides are a synthetically attractive source of sulfonyl radicals in photoredox catalysis and are useful precursors in the synthesis of sulfones. Sulfamoyl chlorides, on the other hand, remain poorly represented despite their similar potential. In this study, N-chlorosulfonylated beta-lactams were prepared from readily available precursors and utilized in an atom transfer radical addition (ATRA) reaction with a variety of olefins, producing beta-lactam sulfonamides in 49-95% yields. beta-Lactams fused to a dihydro-1,2-thiazine ring which closely resemble carbacephems, a widely used class of antibiotics, were also synthesized by an intra-molecular ATRA reaction. This methodology enables the preparation of beta-lactam sulfonamides, a class of compounds that are of great interest in pharmacology. image

Functionalization of C-H bonds has emerged as a powerful strategy for converting inert, nonfunctional C-H bonds into their reactive counterparts. A wide range of C-H bond functionalization reactions has become possible by the catalysis of metals, typically from the second row of transition metals. First-row transition metals can also catalyze C-H functionalization, and they have the merits of greater earth-abundance, lower cost and better environmental friendliness in comparison to their second-row counterparts. C-H bond alkylation is a particularly important C-H functionalization reaction due to its chemical significance and its applications in natural product synthesis. This review covers Ni-catalyzed C-H bond alkylation reactions using alkyl halides and olefins as alkyl sources.