Applications of alkyl orthoesters as valuable substrates in organic transformations, focusing on reaction media

Synthesis of dispiro-orthoester via an acetal oxo-carbenium ion

The first dispiro orthoester via a spiroacetal oxo-carbenium ion is presented. Oxidative dearomatization of phloretic esters results in a bifunctional electrophilic spiroacetal oxo-carbenium ion, which undergoes a double nucleophilic addition by diol delivering a range of unusual dispiro-orthoesters with an excellent diversity.

5-Aza-adenine Derivatives for Crop-Protection: Multicomponent Synthesis, Experimental and Theoretical Structural Analysis

A microwave-assisted synthesis of 7-amino-1,2,4-triazolo[1,5-a][1,3,5]triazine-2-propanamides was developed using a three-component, catalyst-free reaction of cyanamide and trimethyl orthoformate with 3-(5-amino-1H-1,2,4-triazol-3-yl)propanamides (3). The reaction tolerated structurally diverse substrates and proceeded chemo- and regio-selectively, affording the target compounds in high purity in 5-10 minutes. The convenient chromatography-free isolation and purification of the products add practicality to this method. The structural features of the prepared compounds were investigated using dynamic NMR spectroscopy, X-ray crystallography and computational chemistry calculations. X-ray crystallography performed on a representative compound, 3-(7-amino-1,2,4-triazolo[1,5-a][1,3,5]triazin-2-yl)-N-(4-benzyl)propanamide (4 l), showed the overall molecular conformation to adopt the shape of the letter C. Notable localisation of π-electron density is found within the 1,2,4-triazolo[1,5-a][1,3,5]triazine system; a relatively short C-NH2 bond is consistent with restricted rotation about this bond. This study also presents a detailed analysis of the molecular interactions in 4 l using DFT and QTAIM methods with a focus on the hydrogen-bonding and π-stacking interactions that influence the molecular packing of 4 l. The findings reveal the significant roles of N-H⋅O, N-H⋅N and C-H⋅N interactions, along with electrostatically enhanced π⋅π contacts. A broad screening for insecticidal, fungicidal and herbicidal properties identified several compounds with potent herbicidal activity against Matricaria inodora.

Inhibition of Botrytis cinerea in tomatoes by allyl-isothiocyanate release from black mustard (Brassica nigra) seeds and detection by E-nose

The aim of this work is to delayed the postharvest development of Botrytis cinerea in tomatoes by releasing allyl-isothiocyanate (AITC) from mustard seeds at room temperature, and to discriminate the aromatic profile by using an electronic device (E-nose). Olfactory sensory analysis showed that tomatoes inoculated in the presence of AITC did not develop the microorganisms until the eighth day of storage. The highest inhibitory concentration of AITC was found in Day 3 (175.18 ppb). However, tomatoes inoculated without the presence of AITC developed a moldy aroma on the third day of storage. The most prominent chemical groups were esters, ketones and alcohols. The compounds associated with a positive aroma were trimethyl orthoacetate, styrene, tridecan-7-amine and acetaldehyde, while compounds related to B. cinerea were hepten-2-one and butanoic acid. The E-nose was able to discriminate tomatoes based on their aromatic characteristics during the storage period. Moreover, it successfully quantified the mold defect aroma with the established Partial Least Squares (PLS) model.

Synthesis of pyranobenzopyrans from D-glucal using ionic liquids

Imidazolium room temperature ionic liquids (RTILs) were used as solvents in the Lewis acid-catalyzed cycloaddition reactions of D-glucal with substituted salicylaldehydes. These reactions selectively led to various, novel, cis-pyrano [4,3-b]benzopyrans in modest yields, different products than those isolated from analogous solution studies. Furan diol was isolated as the major byproduct from all the reactions. The use of RTILs facilitated the use of unprotected sugars in these reactions.

Design, synthesis and molecular docking of new fused 1H-pyrroles, pyrrolo[3,2-d]pyrimidines and pyrrolo[3,2-e][1, 4]diazepine derivatives as potent EGFR/CDK2 inhibitors

A new series of 1H-pyrrole (6a-c, 8a-c), pyrrolo[3,2-d]pyrimidines (9a-c) and pyrrolo[3,2-e][1, 4]diazepines (11a-c) were designed and synthesised. These compounds were designed to have the essential pharmacophoric features of EGFR Inhibitors, they have shown anticancer activities against HCT116, MCF-7 and Hep3B cancer cells with IC₅₀ values ranging from 0.009 to 2.195 µM. IC₅₀ value of doxorubicin is 0.008 µM, compounds 9a and 9c showed IC₅₀ values of 0.011 and 0.009 µM respectively against HCT-116 cells. Compound 8b exerted broad-spectrum activity against all tested cell lines with an IC₅₀ value less than 0.05 µM. Compound 8b was evaluated against a panel of kinases. This compound potently inhibited CDK2/Cyclin A1, DYRK3 and GSK3 alpha kinases with 10-23% compared to imatinib (1-10%). It has also arrested the cell cycle of MCF-7 cells at the S phase. Its antiproliferative activity was further augmented by molecular docking into the active sites of EGFR and CDK2 cyclin A1.

A pH-responsive crosslinker platform for antibody-drug conjugate (ADC) targeting delivery

We report a new 1-6 self-immolative, traceless crosslinker derived from the natural product gallic acid. The linker acts through a pH-dependent mechanism for drug release. This 5-(hydroxymethyl)pyrogallol orthoester derivative (HMPO) was stable for 24 hours at pH values of 7.4 and 6.6 and in plasma, releasing molecules bound to the hydroxymethyl moiety under acid-dependent stimuli at pH 5.5. The linker was non-toxic and was used for the conjugation of Doxorubicin (Doxo) or Combretastatin A4 with Cetuximab. The ADCs formed showed their pH responsivity reducing cell viability of A431 and A549 cancer cells better than Cetuximab alone.