Polyaddition of bifunctional 1,3‐benzoxazine and 2‐methylresorcinol

A polyaddition system consisted of a bifunctional N‐n‐propyl benzoxazine and 2‐methylresorcinol ( MR ) that proceeds at ambient temperature has been developed. In this system, the aromatic ring of MR acted as a bifunctional monomer, reacting with a two equivalent amount of benzoxazine moieties via their ring‐opening reaction. The polyaddition gave the corresponding linear polymer bearing phenolic moieties bridged by Mannich‐type linkage in the main chain. The linear polymer had a high glass transition temperature, which was comparable to that of the linear polybenzoxazine synthesized by the ring‐opening polymerization of a monofunctional N‐n‐propyl benzoxazine. The employment of a bifunctional N‐allyl benzoxazine in the polyaddition system resulted in the formation of the corresponding polymer with allyl pendants, which exhibited improved heat resistance due to its thermally induced crosslinking reaction. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3867–3872     

Finite‐field method with unbiased polarizable continuum model for evaluation of the second hyperpolarizability of an open‐shell singlet molecule in solvents

The static second hyperpolarizability γ of the complexes composed of open‐shell singlet 1,3‐dipole molecule involving a boron atom and a water molecule in aqueous phase are investigated by the finite‐field (FF) method combined with a standard polarized continuum model (PCM) and with a newly proposed unbiased PCM (UBPCM). On the basis of the comparison with the results calculated by the FF method using the full quantum and the quantum‐mechanical/molecular‐mechanical and molecular‐dynamics (QM/MM‐MD) treatments, the present FF‐UBPCM method is demonstrated to remedy the artificial overestimation of the γ caused by standard FF‐PCM calculations and to well reproduce the FF‐QM/MM‐MD and FF‐full‐QM results with much lower costs. © 2013 Wiley Periodicals, Inc.     

N-Phenylation of N-Arylaminophthalimides with Triphenylbismuth and Cupric Acetate: A Convenient Synthesis of 1-Aryl-1- Phenylhydrazines

Synthesis of 1-aryl-1-phenylhydrazines (2) from N-aryl-N-phenylaminophthalimides (1) which were synthesized by the phenylation of 1 with triphenylbismuth and cupric acetate is described.     

Guianofruits C–I from fruit oil of andiroba (Carapa guianensis,Meliaceae)

Two novel chukrasone-type limonoids, named Guianofruits C and D (1 and 2), a guianolide derivative named Guianofruit E (3), and four novel phragmalin–type limonoids named Guianofruits F–I (4–7), were isolated from the fruit oil of Carapa guianensis AUBLET (Meliaceae), a traditional medicine in Brazil and Latin American countries. Their structures were mainly elucidated based on spectroscopic analyses using 1D and 2D NMR techniques. The effects of compounds 1–6 on the production of NO by LPS-activated mouse peritoneal macrophages were investigated. Two new chukrasone-type limonoids, Guianofruits C (1) and D (2), exhibited moderate inhibitory activities.     

Iron-catalyzed δ-selective conjugate addition of methyl and cyclopropyl Grignard reagents to α,β,γ,δ-unsaturated esters and amides

Iron-catalyzed δ-selective conjugate addition of methyl and cyclopropyl Grignard reagents to α,β,γ,δ-unsaturated esters and amides took place in good yields to give products exclusively with cis-β,γ-olefinic bond.     

Surface-deformation characteristics of uniaxially oriented poly(ethylene terephthalate) film as evaluated from nanoscratch tests with scanning probe microscopy

The surface-deformation characteristics of uniaxially drawn poly(ethylene terephthalate) (PET) film were successfully evaluated with multiline scratch tests using scanning probe microscopy (SPM) on a nanometer scale. The PET film was prepared by compression molding from the melt, followed by quenching in ice water. The obtained amorphous film was drawn uniaxially below its glass-transition temperature, and the resultant surface roughness could be reduced to within 5 nm. A multiline scratch with the Si(3)N(4) tip of an SPM on the oriented PET surface was made parallel and perpendicular to the drawing axis under applied loads of 5-30 nN. The perpendicular scratching generated a characteristic periodic pattern on the film surface, but the parallel scratching induced a tearing of the surface. These results suggest that surface-deformation mechanisms were dominated by molecular anisotropy. The surface-deformation properties, as evaluated from scratch-angle dependences on morphological changes on a nanometer scale, were similar to the mechanical properties of the bulk.     

3-Nitro-l,2,4-triazol-l-yl-tris(pyrrolidin-1-yl)phosphonium hexafluorophosphate (PyNTP) as a condensing reagent for solid-phase peptide synthesis

Solid-phase oligopeptide synthesis has been well developed and most short oligopeptides can now be easily synthesized. However, when a desired oligopeptide forms a secondary structure or includes less reactive amino acids such as aminoisobutyric acid, its terminal amino groups become less reactive and synthesis of the desired oligopeptides becomes difficult. To expand the number of synthetic peptide sequences, we have developed efficient coupling conditions using 3-nitro-l,2,4-triazol-l-yl-tris(pyrrolidin-1-yl)phosphonium hexafluorophosphate (PyNTP) as a highly reactive condensing reagent on an unswellable solid support. PyNTP demonstrated higher reactivity than conventional condensing reagents and the optical purity of the synthesized oligopeptides was sufficiently high for application to general oligopeptide synthesis.     

Diels–Alder Reaction on Free C68 Fullerene and Endohedral Sc3N@C68 Fullerene Violating the Isolated Pentagon Rule: Importance of Pentagon Adjacency

The reaction mechanism and regioselectivity of the Diels–Alder reactions of C₆₈ and Sc₃N@C₆₈, which violate the isolated pentagon rule, were studied with density functional theory calculations. For C₆₈, the [5,5] bond is the most favored thermodynamically, whereas the cycloaddition on the [5,6] bond has the lowest activation energy. Upon encapsulation of the metallic cluster, the exohedral reactivity of Sc₃N@C₆₈ is reduced remarkably owing to charge transfer from the cluster to the fullerene cage. The [5,5] bond becomes the most reactive site thermodynamically and kinetically. The bonds around the pentagon adjacency show the highest chemical reactivity, which demonstrates the importance of pentagon adjacency. Furthermore, the viability of Diels–Alder cycloadditions of several dienes and Sc₃N@C₆₈ was examined theoretically. o‐Quinodimethane is predicted to react with Sc₃N@C₆₈ easily, which implies the possibility of using Diels–Alder cycloaddition to functionalize Sc₃N@C₆₈.