Stereoselective synthesis of C3–C17 and C18–C34 subunits of bullatanocin utilizing α-chloro sulfide intermediates

A convergent synthesis of bullatanocin is envisaged by the union of C18–C34, C3–C17 and the butenolide subunits. The synthesis of the C3–C17 and C18–C34 subunits is disclosed that takes advantage of the chirality of tartaric acid for 1,2-asymmetric induction, chloro sulfides for carbon chain elongation and [2,3] sigmatropic shift for the preparation of 1,4-diol moiety via efficient 1,3-chirality transfer. The THF ring is elaborated by intramolecular displacement.     

Hypervalent organoselenium compounds stabilized by intramolecular coordination: synthesis and crystal structures

Two novel hypervalent selenium(IV) compounds stabilized by intramolecular interactions, namely 6‐phenyl‐6,7‐dihydro‐5H‐2,3‐dioxa‐2aλ⁴‐selenacyclopenta[hi]indene, C₁₄H₁₂O₂Se, 14 , and 5‐phenyl‐5,6‐dihydro‐4H‐benzo[c][1,2]oxaselenole‐7‐carbaldehyde, C₁₄H₁₂OSe₂, 15 , have been synthesized by the reaction of 2‐chloro‐1‐formyl‐3‐(hydroxymethylene)cyclohexene with in‐situ‐generated disodium diselenide (Na₂Se₂). The title compounds were characterized by FT–IR spectroscopy, ESI–MS, and single‐crystal X‐ray diffraction studies. For 14 , there is whole‐molecule disorder, with occupancies of 0.605 (10) and 0.395 (10), a double bond between C and Se, and the five‐membered selenopentalene rings are coplanar. The packing is stabilized by π–π stacking interactions involving one of the five‐membered Se/C/C/C/O rings [centroid–centroid (Cg…Cg) distance = 3.6472 (18) Å and slippage = 1.361 Å], as well as C—H…π interactions involving a C—H group and the phenyl ring. In addition, there are bifurcated C—H…Se,O interactions which link the molecules into ribbons in the c direction. For 15 , the C—Se bond lengths are longer than those of 14 . The two five‐membered rings are coplanar. There are no π–π or C—H…π interactions; however, molecules are linked by C—H…O interactions into centrosymmetric dimers, with graph‐set notation R₂²(16).     

Protein‐based bioadhesives and bioglues

Bioadhesives and glues are widely used as an adjunct to conventional methods employed in healing the post‐surgical injuries and restoration of normal tissue functions. Protein‐based bioadhesives have been used for a long time, and they are a more biocompatible alternative compared with synthetic adhesives. They offer advantages such as ease of application, reduction in surgery time, improved quality and strength of the seal, and effective sealing. Also, bioadhesives are being exploited in different fields like controlled and site‐specific drug delivery systems, and in tissue engineering and regeneration. There are various marketed protein‐based glues that are available in different forms. Thus, all in all, it is a patient compliant system, thereby increasing its recent popularity. This article provides insight into different types and sources of protein‐based bioadhesives, their history of use, mechanism of adhesion. and various products that have been approved by the regulatory authorities for clinical use. It also includes information regarding the products in clinical trials and potential applications.     

Design,Synthesis, and Anticancer Activity of 1,2,3-Triazole Likned Thiazole-1,2-isoxazole Derivatives

Russian Journal of General Chemistry - A series of novel 1,2,3-triazole linked thiazole-1,2-isoxazole derivatives has been designed, synthesized and characterized by 1H and 13C NMR, and mass...     

Development and physicochemical characterization of doxorubicin-encapsulated hydroxyapatite–polyvinyl alcohol nanocomposite for repair of osteosarcoma-affected bone tissues

Nowadays locoregional therapy for cancer treatment can be associated with nanocomposite drug delivery systems. Coated nanoparticles have versatile applications for delivering chemotherapeutic drugs to the targeted part of the body. In this study, a ceramic carrier like nanosized hydroxyapatite (HAp) was synthesized by the in situ precipitation method followed by coating with anticancer drug like doxorubicin (DOX) and polyvinyl alcohol (PVA) polymer. The physicochemical characterization of the prepared polymer-coated drug ceramic nanocomposite (DOX-HAp-PVA) was carried out using Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron spectroscopy, and particle size distribution. Furthermore, the biocompatibility and the anticancer activity of the nanocomposite were explored by MTT assay study. Successfully synthesized DOX-HAp-PVA nanocomposite exhibited a remarkable cytotoxicity toward osteosarcoma cells (MG 63), which may be potentially used as an anticancer agent against osteosarcoma.     

Solution-phase parallel synthesis of substituted benzimidazoles

A solution-phase parallel synthesis of o-phenylenediamines is described. These intermediates were then subsequently converted to benzimidazole scaffolds (three-point diversity) in excellent purities and yields. High-throughput purification of this multistep synthetic sequence was accomplished using polymer-bound scavengers and reagents and liquid-liquid extraction protocols.     

Circumferential-wave phase velocities for empty,fluid-immersed spherical metal shells

In earlier studies of acoustic scattering resonances and of the dispersive phase velocities of surface waves that generate them [see, e.g., Talmant et al., J. Acoust. Soc. Am. 86, 278-289 (1989) for spherical aluminum shells] we have demonstrated the effectiveness and accuracy of obtaining phase velocity dispersion curves from the known acoustic resonance frequencies. This possibility is offered through the condition of phase matching after each complete circumnavigation of these waves [Uberall et al., J. Acoust. Soc. Am. 61, 711-715 (1977)], which leads to a very close agreement of resonance results with those calculated from three-dimensional elasticity theory whenever the latter are available. The present investigation is based on the mentioned resonance frequency/elasticity theory connection, and we obtain comparative circumferential-wave dispersion-curve results for water-loaded, evacuated spherical metal shells of aluminum, stainless steel, and tungsten carbide. In particular, the characteristic upturn of the dispersion curves of low-order shell-borne circumferential waves (A or A0 waves) which takes place on spherical shells when the frequency tends towards very low values, is demonstrated here for all cases of the metals under consideration.     

Dissociation rate measurements in SO2 + Ar mixtures behind incident shock waves

Dissociation rates of SO₂ in SO₂ + Ar mixtures at 6%, 11%, 15% and 20% of SO₂ were measured behind incident shock waves over a temperature range 4000–6000 K at initial pressures 1.0 to 2.5 Torr. The recorded laser schlieren signals exhibited two exponentials, the faster one due to vibrational relaxation and the slower one due to dissociation. The initial dissociation rate was calculated from the value of the density gradient at the point of intersection of the two exponentials. A least-squares analysis of the experimental data yielded the following empirical relations: k_SO2Ar = 3.34 × 10¹⁵ exp(?107.6 kcal mole^?1/RT) cm³/mole s, k_SO2SO2 = 5.02 × 10¹⁴ exp(?66.6 kcal mole^?1 kcal mole^?1/RT) cm³/mole s.