A Facile Synthesis of Bridged Polycyclic Naphthooxazocine Skeletons: Eight‐Membered‐Ring Constructions via Tandem Dinucleophilic Addition of Naphthalenols to Quinolinium Salts

The efficient synthesis of bridged polycyclic naphthooxazocines 3 via addition of naphthalenols 1 as a bis‐nucleophile to N‐alkylquinolinium salts 2 is described (Scheme 1 and Table 2). This new approach provides a powerful entry into polycyclic structures containing bicyclic N,O‐acetals related to bioactive compounds.     

Facile and one-pot,electro-organic synthesis of a new bis-quinone by the ECCE mechanism in green media

Electrochemical oxidation of 4-methyl catechol(1a) is investigated in the presence of 1,3-indandione(3)as nucleophile in phosphate buffer solution(0.2 mol/L,pH 6) mixed with ethanol as organic green solvent(50/50) using cyclic voltammetry and controlled-potential coulometry.The results indicated thatquinones derived from electro-oxidation of 1a,participated in a 1,4-Michael addition reaction with1,3-indandione(3) under ECCE mechanism.In this direction,a new bis-quinone was synthesized in high yield and good purity using a facile and convenient electrochemical pathway by carbon anode electrodes in an undivided cell.     

PbS nanoparticles stabilized on HPG-modified FeNi3 as catalyst for synthesis of 2-amino-4H-chromene under mild conditions

FeNi₃\SiO₂\HPG\PbS magnetic nanoparticles (MNPs) catalyst was readily prepared from inexpensive starting materials in aqueous media which catalyzed the synthesis 2-amino-4H-chromene via intermittent microwave irradiation. X-ray diffraction, transmission electron micrographs, and scanning electron micrographs were employed to characterize the properties of the synthesized FeNi₃\SiO₂\HPG\PbS MNPs. High catalytic activity and ease of recovery from the reaction mixture using external magnet and several reuse times without significant losses in performance are additional eco-friendly attributes of this catalytic system.     

Synthesis and anticancer activity of some new pyridine derivatives

Different substituents were introduced in positions 2 and 6 of 2,6 diaminopyridine in order to obtain new heterocyclic compounds. A new series of aza pyridine, imidazopyridine, benzodiazepine, indole, pyrimidine, and benzimidazole heterocyclic derivatives were synthesized in good yields. The anticancer activities of some of the new compounds were evaluated against liver cancer cell line HEPG2. Compounds 3, 4, 10, 11, 12, and 17 showed the highest activity when compared to 5-flurouracil (5-FU) and doxorubicin (DOX) chemotherapy.     

Cayley’s hyperdeterminant: A combinatorial approach via representation theory

Cayley’s hyperdeterminant is a homogeneous polynomial of degree 4 in the 8 entries of a $2\times 2\times 2$ array. It is the simplest (nonconstant) polynomial which is invariant under changes of basis in three directions. We use elementary facts about representations of the 3-dimensional simple Lie algebra $\mathfrak{s}{l}_2(\mathbb{C})$ to reduce the problem of finding the invariant polynomials for a $2\times 2\times 2$ array to a combinatorial problem on the enumeration of $2\times 2\times 2$ arrays with non-negative integer entries. We then apply results from linear algebra to obtain a new proof that Cayley’s hyperdeterminant generates all the invariants. In the last section we discuss the application of our methods to general multidimensional arrays.     

Frequency dependent beating patterns and amplitude increase during the approach of an internal wave packet

A frequency-dependent beating pattern in the spectrogram of broadband signals transmitted during the approach of an internal wave packet to an acoustic propagating path is reported. An analytical expression relating the acoustic signal measurements and environmental parameters under certain conditions is obtained. Three-dimensional parabolic equation modeling results compare well with Shallow Water 2006 experiment data.