Beilstein Journal of Organic Chemistry最新文献

[n]Phenacenes ([n] = 5-7), octafluorinated at the terminal benzene rings (F₈-phenacenes: F ₈ PIC, F ₈ FUL, and F ₈ 7PHEN), were photochemically synthesized, and their electronic spectra were investigated to reveal the effects of the fluorination on the electronic features of phenacene molecules. F₈-Phenacenes were conveniently synthesized by the Mallory photoreaction of the corresponding fluorinated diarylethenes as the key step. Upon fluorination on the phenacene cores, the absorption and fluorescence bands of the F₈-phenacenes in CHCl₃ systematically red-shifted by ca. 3-5 nm compared to those of the corresponding parent phenacenes. The vibrational progressions of the absorption and fluorescence bands were little affected by the fluorination in the solution phase. In the solid state, the absorption band of F₈-phenacenes appeared in the similar wavelength region for the corresponding parent phenacenes whereas their fluorescence bands markedly red-shifted and broadened. These observations suggest that the intermolecular interactions of excited-state F₈-phenacene molecules are significantly different from those of the corresponding parent molecules, most likely due to different crystalline packing motifs.

Fluorinated amino acids are essential building blocks in the spheres of protein engineering and medicinal chemistry. In the last decades, a large number of different synthetic strategies have been developed to produce a large variety of fluorinated amino acids. Still, obtaining fluorinated amino acids in great quantities can be challenging, or the corresponding pathways are heavily time-consuming and synthetically challenging. In this context, chiral Ni(II) complexes can be powerful tools to obtain tailor‑made non‑canonical amino acids. In this work, we wanted to take advantage of this strategy and extend the range of this method to include additional fluorinated amino acids. We synthesized two fluorinated analogs of phenylalanine, which are still unexplored in the context of peptide and protein chemistry. Furthermore, both diastereomers of trifluoroleucine were synthesized, demonstrating that the described strategy can also be applied to synthesize enantio‑ and diastereomerically pure γ‑branched fluorinated amino acids. This work further underlines the importance of chiral Ni(II) complexes in the synthesis of fluorinated amino acids.

The transition-metal-catalyzed asymmetric allylic substitution represents a pivotal methodology in organic synthesis, providing remarkable versatility for complex molecule construction. Particularly, the generation and utilization of chiral secondary alkylcopper species have received considerable attention due to their unique properties in stereoselective allylic substitution. This review highlights recent advances in copper-catalyzed asymmetric allylic substitution reactions with chiral secondary alkylcopper species, encompassing several key strategies for their generation: stereospecific transmetalation of organolithium and organoboron compounds, copper hydride catalysis, and enantiotopic-group-selective transformations of 1,1-diborylalkanes. Detailed mechanistic insights into stereochemical control and current challenges in this field are also discussed.

The electrochemical synthesis of 2-aminoprolines based on anodic decarboxylation-intramolecular amidation of readily available N-acetylamino malonic acid monoesters is reported. The decarboxylative amidation under Hofer-Moest reaction conditions proceeds in an undivided cell under constant current conditions in aqueous acetonitrile and provides access to N-sulfonyl, N-benzoyl, and N-Boc-protected 2-aminoproline derivatives.

Antibody-drug conjugates (ADCs) represent a promising class of targeted therapeutics, combining the specificity of antibodies with the potency of cytotoxic drugs to enhance therapeutic efficacy while minimizing off-target effects. The development of new chemical methods for bioconjugation is essential to generate ADCs and to optimize their stability, efficacy, and safety. Traditional conjugation methods often face challenges related to site-selectivity and heterogeneous product mixtures, highlighting the need to develop new, innovative chemical strategies. Photoredox chemistry emerges as a powerful tool in this context, enabling precise, mild, and selective modifications of peptides and proteins. By harnessing light to drive chemical transformations, photoredox techniques can facilitate the synthesis of antibody bioconjugates. This perspective will discuss the drive to develop and empower photoredox methods applied to antibody functionalization.

Massarilactones constitute a rare class of polyketides produced mainly by endophytic fungi. Given that semisynthetic derivatives often exhibit biological activities greater than those of the substrates, seven previously unreported derivatives of massarilactone D, compounds 2-8, were synthetized by acylation with methacryloyl chloride, cinnamoyl chloride, 4-bromobenzoyl chloride, trans-2-methyl-2-butenoyl chloride, and crotonyl chloride. These compounds were evaluated for their cytotoxic activity against the murine fibroblasts L929, human cervix carcinoma KB-3-1, human lung carcinoma A549, human prostate cancer PC-3, epidermoid carcinoma A431, ovarian carcinoma SKOV-3, and breast cancer MCF-7 cell lines. Compounds 2 and 3 exhibited significant cytotoxicity against all the tested cells. Some of the semisynthetic derivatives were also tested for their nematicidal activity and compound 4 displayed significant and selective nematicidal activity with LD₉₀ and LD₅₀ of 100 and 12.5 µg/mL, respectively. Since the parent compound was not active, the present study supports the fact that the acylation reaction can improve bioactivities of some natural products.

The total synthesis of (±)-simonsol C was accomplished using a dearomatization under acidic conditions as key step to construct an aryl-containing quaternary center. The 6/5/6 benzofuran unit was formed through reductive elimination with Zn/AcOH and a spontaneous oxy-Michael addition. This synthesis consists of 8 steps and achieves an overall yield of 13%, making it the shortest known route.

The hydantoin scaffold is renowned for its wide-ranging biological activities, including antibacterial, antiviral, anticancer, anti-inflammatory, and anticonvulsant effects. In this study, we present an innovative, sustainable approach to synthesizing hydantoins (H2a-j) directly from amino acids. This method employs a column chromatography-free, two-step, one-pot microwave-assisted synthesis that delivers hydantoins in yields ranging from 34% to 89%. The protocol demonstrates exceptional functional group tolerance, accommodating phenyl, aliphatic, phenol, alcohol, heterocyclic, and sulfide groups. This scalable, rapid, and eco-friendly strategy offers a promising avenue for the efficient synthesis of hydantoins, aligning with green chemistry principles and expanding the accessibility of these bioactive compounds for pharmaceutical applications.

Formaldehyde emerges as a cornerstone in multicomponent reactions, mainly prized for its robust reactivity. Yet, alongside these beneficial traits, this highly reactive C1-building block raises concerns, primarily regarding its toxicity. One notable issue is the challenge of controlling the formation of undesired byproducts during its reactions. This review explores alternative C1-building blocks that serve as surrogates for formaldehyde, aiming to mitigate some of the challenges associated with its use in multicomponent reactions. By identifying these alternatives, toxicity concerns and improved reaction control can be addressed, paving the way for more efficient and sustainable synthetic methodologies.

For the first time, the reaction of substituted 2H-furo[3,2-b]pyran-2-ones with diverse N-nucleophiles was investigated. It was shown that the direction of the process depends on the type of employed nitrogen-containing reagent. For example, condensation with aliphatic amines leads to 2H-furo[3,2-b]pyran-2,7(3H)-diones bearing an exocyclic enamine moiety. At the same time, interaction with dinucleophiles results in recyclization accompanied by opening of the furan ring. Relied on the aforementioned process a general method for the synthesis of substituted pyrazol-3-ones with allomaltol fragment was designed. Structures of representatives of all obtained products were unambiguously confirmed by X-ray diffraction.