ABSTRACT A series of novel 5-substituted 2-[2-(pyridyl)ethenyl]-1,3,4-oxadiazoles were efficiently synthesized by cyclocondensation of the appropriate 3-(pyridyl)acrylohydrazides with triethyl orthoesters in the presence of glacial acetic acid. The products were identified by means of spectroscopic methods and their pKA ionization constants were determined. The influence of substituents on the ...

A new, convenient, efficient, and cost-effective one-pot synthesis of 1Hphenanthro[9,10]imidazol-2-yl from phenanthraquinone and aldehydes, using sulfuric acidimmobilized on silica as catalyst is described. The present methodology offers severaladvantages such as excellent yields, simple procedure, shorter reaction times, the use ofinexpensive reagents, easy recovery and eco-friendly. In additi...

a new, convenient, efficient, and cost-effective one-pot synthesis of 1hphenanthro[9,10]imidazol-2-yl from phenanthraquinone and aldehydes, using sulfuric acidimmobilized on silica as catalyst is described. the present methodology offers severaladvantages such as excellent yields, simple procedure, shorter reaction times, the use ofinexpensive reagents, easy recovery and eco-friendly. in additi...

Propargyl 1,2-O-orthoesters are exploited for the synthesis of 1,2-trans O-glycosides of protected amino acids. N-Fmoc- and N-Cbz protected serine/threonine - benzyl/methyl esters reacted well with glucosyl-, galactosyl-, mannosyl- and lactosyl- derived propargyl 1,2-orthoesters affording respective 1,2-trans glycosides in good yields under AuBr(3)/4 Å MS Powder/CH(2)Cl(2)/rt. t-Boc serine deri...

Reversible covalent reactions have become an important tool in supramolecular chemistry and materials science. Here we introduce the acid-catalyzed exchange of O,O,O-orthoesters to the toolbox of dynamic covalent chemistry. We demonstrate that orthoesters readily exchange with a wide range of alcohols under mild conditions and we disclose the first report of an orthoester metathesis reaction. W...

High molecular weight sugar poly(orthoesters) were synthesized through reverse anomeric effect (RAE). We demonstrated that when RAE-enabled promoters, such as 4-(dimethylamino)pyridine (DMAP), triphenylphosphine (TPP) or imidazole, were employed, efficient polymerizations were achieved, giving sugar poly(orthoesters) with molecular weights up to 18 kDa.

The identification of cross-over products in the rearrangement of two structurally similar sugar 1,2-orthoesters to glycosidic products is reported.

We demonstrate stereolithographic 3D printing of pure aliphatic poly(ether esters) from spiro-orthoesters with near-net-zero shrinkage and significantly reduced stress.

Nine new phragmalin-type limonoid orthoesters, tabulalides F-N (1-9), together with three known compounds, tabulalides C and D, and tabularisin N (10-12), were isolated from the stem bark of Chukrasia tabularis var. velutina. Extensive spectroscopic technologies were applied to elucidate the structures of these new compounds, including the application of circular dichroism (CD) exciton chiralit...

Rats treated with a single dose of triethyl lead chloride (TEL) by subcutaneous injection (7.9 mg/kg) showed a transient increase in latencies to lick the hind paw during hot-plate testing. The time course of triethyl lead-induced antinociception was temporally associated with depressed binding capacity of benzodiazepine receptor sites and reduced levels of Substance P. Both of these changes ap...