Density functional study of ethylamine and allylamine on Si(1 0 0)-2 × 1 and Ge(1 0 0)-2 × 1 surfaces

We have investigated the interactions of ethylamine and allylamine with models of the Si(1 0 0)-2 × 1 and Ge(1 0 0)-2 × 1 semiconductor surfaces. Ab initio molecular orbital calculations, along with density functional theory (DFT), are used to examine the interaction of these amines with cluster models of the semiconductor surfaces. The transition states and final adsorption products for adsorption of the molecules are predicted. The DFT calculations show the amines form N-dative bond states with Si(1 0 0)-2 × 1 or Ge(1 0 0)-2 × 1 as the initial adsorption product. The initial dative-bond products can be further activated, resulting in N-H bond cleavage on both surfaces. The overall reaction of a given amine on Si(1 0 0) via N-H dissociation is more exothermic than on the Ge(1 0 0) surface.     

Optimization of Preparation Process for Allylamine-bacterial Cellulose via Graft Copolymerization by Response Surface Methodology

In order to improve the efficiency of new adsorbent, grafting-allylamine bacterial cellulose（al-BC）, response surface methodology（RSM） was used for the optimization of preparation process. Three factors affecting the yield of grafting reaction are the amount of allylamine, the concentration of ceric ammonium nitrate（CAN） and the concentration of nitric acid. Based on the regression coefficient analysis in the Box-Behnken design, a relationship between the preparation variable and grafting yield was obtained. Square error analysis on main factors, and multi-variable interactions were employed for studying grafting yield. The results show that at the conditions of CAN of 23.00 mmol/L CAN, 0.17 mol/L nitric acid, adding an amount of grafting-allylamine bacterial cellulose of 26.49 mL/L made grafting rate reach maximum of 24.25% at 40℃ after the reaction for 4 h. The experimental results are in good agreement with the calculation values via proposed regression equation, indicating that the equation could be used to nredict and optimizate the preparation of grafting al-BC.     

Low-energy electrons and X-ray irradiation effects on plasma-polymerized allylamine bioactive coatings for stents

Radiation used in biomedical applications causes chemical changes to biomedical materials. This work is an ex situ simulation of the influence of low-energy electron (LEE) impact and X-ray irradiation on the chemical properties of plasma-polymerized allylamine (PPA) bioactive and biocompatible stent coatings. Preliminary X-ray photoelectron spectroscopy (XPS) results show that PPA coatings oxidize in contact with ambient air by the detection of C-O and CO bonds which are typical of polymer oxidation. Chemical changes after LEE and X-ray irradiation are mainly a loss of oxygen, assuming a surface deoxidizing and not a complete destruction of the surface. XPS survey analyses show that the amine groups remain stable during irradiation. LEE impact measurements by TOF mass spectrometry show that the main ionic losses are H⁻ ions. It appears that CN groups are stable under irradiation and we observe a loss of hydrogen and oxygen as the main chemical modifications. In conclusion, these results suggest that PPA coatings are stable under biomedical radiation, and they can therefore be used for bioactive and biocompatible stent coatings.     

Allylamine Derivatives—a New Class of Active Substances in Antifungal Chemotherapy

Fungal infections (mycoses) are found throughout the world. Only a few structural classes of compounds currently satisfy the demands of modern chemotherapy in their treatment; hence, the quest for new types of active substances is of major scientific and therapeutic importance. The first representative of a new class of substances–the allylamine derivatives–namely naftifine ((E)-N-methyl-N-(1-naphthylmethyl)-3-phenylallylamine) was discovered by accident and has recently become commercially available as a topical antimycotic. The exploration of structure-activity relationships on the basis of naftifine and new synthetic strategies led to the discovery of the currently most active compound of this type, terbinafine, the first pharmaceutical agent to contain a (E)-1, 3-enyne structural element. Terbinafine exhibits considerably higher activity than the original “lead” structure naftifine both in vitro and in vivo; it is also up to one order of magnitude more effective than standard preparations in various chemotherapeutic animal tests after topical or oral administration. According to clinical experience gained so far, terbinafine is well tolerated and shows promising activity against various types of mycoses. Allylamines act as potent, selective inhibitors of fungal squalene epoxidase via a novel mechanism, which, unlike in the case of other inhibitors of steroid biosynthesis, does not depend on cytochrome P450.     

Asymmetric Synthesis of α,α‐Disubstituted Allylic Amines through Palladium‐Catalyzed Allylic Substitution

The first asymmetric synthesis of important α,α‐disubstituted N‐alkyl allyl amine scaffolds through allylic substitution is reported. This approach is based on palladium catalysis and features ample scope with respect to both the allylic precursor and amine reagent, and high asymmetric induction with enantiomeric ratios (e.r.) up to 98.5:1.5. The use of less‐reactive anilines is also feasible, providing enantioenriched α,α‐disubstituted N‐aryl allylic amines.     

Synthesis of dihydropyrazolo[4,3-c]azepines via iodine-mediated intramolecular hydrative cyclization

A straightforward approach to substituted dihydropyrazolo[4,3-c]azepines via I₂-mediated intramolecular hydration in pyrazole-based allylamines prepared from Morita–Baylis–Hillman adducts of 4-iodopyrazolealdehyes is described.