Preparation of New Nitrogen-Bridged Heterocycles. 34. Synthesis and Reaction of 2,3-Dihydrooxepino [2,3-b]-indolizines

Article信州大学工学部紀要 74: 31-42 (1994)departmental bulletin pape

Preparation of New Nitrogen-bridged Heterocycles. 12. Reaction of 2-(Acylmethoxy)-3-vinylindolizines in the Presence of a Base

Article信州大学工学部紀要 58: 1-8 (1985)departmental bulletin pape

A New Approach to Imidazo[1,2-a]pyridine Derivatives and Their Application to the Syntheses of Novel 2H-Pyrano[2’,3’:4,5]imidazo[1,2-a]pyridin-2-one Derivatives

3-[Bis(methylthio)methylene]-2(3H)-imidazo[1,2-a]pyridinones were prepared from the S-alkylation of pyridinium 1-[1-carbamoyl-1-[(methylthio) thiocarbonyl]]methylides with methyl iodide followed by the alkaline treatment of the resulting pyridinium salts. The reactions of these 3-methylene-2(3H)-imidazo[1,2-a]pyridinones with some ethyl cyano- or acyl-substituted acetates in the presence of a base did not afford the initially expected 2H-pyrano[2',3':4,5]imidazo[1,2-a]pyridine-2-one derivatives, but, instead of them, provided ethyl 3[2-hydroxyimidazo[1,2-a]pyridin-3-yl]acrylates. The thermolyses of these acrylates without any solvent under reduced pressure gave the corresponding 2H-pyrano[2',3':4,5]imidazo[1,2-a]pyridine-2-one derivatives.ArticleHETEROCYCLES. 80(1):439-454 (2010)journal articl

Preparation of New Nitrogen-Bridged Heterocycles. 68. One-Pot Synthesis of 4-Substituted 5-Acylthieno[3,2-d]thiazole Derivatives

The reactions of 5-acyl-3-(1-pyridinio)thiophene-2-thiolates with dimethyl acetylenedicarboxylate in xylene at the reflux temperature afforded the corresponding 2-unsubstituted 5-acylthieno[3,2-d]thiazoles in 25―69% yields together with dimethyl phthalate as another fragmentation product. In a few reactions, the unexpected products, dimethyl 2-[2-acylthieno[2’,3’:2,3]-1,4-thiazino[4,5-a]pyrrol-8-ylidene]succinate derivatives, were also isolated, though their yields were very low.ArticleHETEROCYCLES. 81(1):175-184 (2010)journal articl

Base-induced Generation of Aryl(1,2,3-triazol-1-yl)carbenes from 1-[(N-Phenylsulfonyl)benzohydrazonoyl]-1,2,3-triazoles and Their Ring Enlargement to 3-Aryl-1,2,4-triazines

The Bamford-Stevens reactions of 1-[N-(phenylsulfonyl)benzohydrazonoyl]-1,2,3-triazole derivatives, readily available from the 1,3-dipolar cycloadditions of N-(phenylsulfonyl)benzohydrazonoyl azides with enamines, were examined and the transformation from aryl(1,2,3-triazol-1 -yl)carbene intermediates to the corresponding 3-aryl-1,2,4-triazine derivatives was first observed.ArticleHETEROCYCLES. 65(2): 279-286 (2005).journal articl

Synthesis of Spiro[2-cyclopentene-1,3’-imidazo[1,2-a]pyridine] Derivatives and Their Interesting Behavior in 1H-NMR Spectra in Deuteriochloroform

Ethyl 2',3'-dihydro-2-methylthio-2',4-dioxospiro[2-cyclopentene-1,3'-imidazo[1,2-a]pyridine]-3-carboxylates were synthesized from the reactions of 3-[bis(methylthio)methylene]-2(3H)-imidazo[1,2-a]pyridinones with ethyl 4-chloroacetoacetate in the presence of a base. The 2-methylthio group in these Spiro compounds was easily replaced with some primary and secondary amines to afford the corresponding 2-amino derivatives. Very interestingly, the proton signals of these Spiro compounds in the H-1-NMR spectra in deuteriochloroform (CDCl3) changed with an increase in the sample concentration, and the analysis for the magnitude and the direction of each proton shift disclosed the conformational change of the cyclopentenone moiety in this molecule.ArticleHETEROCYCLES. 81(9):2075-2086 (2010)journal articl

ASYMMETRIC 1,3-DIPOLAR CYCLOADDITION REACTIONS OF AZOMETHINE IMINES WITH ACROLEIN CATALYZED BY L-PROLINE AND ITS DERIVATIVES

1,3-Dipolar cycloadditions between acrolein and various N,N'-cyclic azomethine imines in the presence of L-proline and its derivatives as organocatalysts were investigated. Reactions that were catalyzed by (S)-indline-2-carboxylic acid (30 mol%) in CHCl3/MeOH 97:3 (v/v) showed high exo-selectivities (exolendo 91:9 similar to 99:1) and enantioselectivities (75 similar to 98% ee). In contrast, reactions catalyzed by L-proline (30 mol%) under similar conditions favored the endo-cycloadduct (83:27 similar to 99:1) with modest to good enantioselectivities (31 similar to 83% ee). Based on our studies, the diastereoselective mechanism of the L-proline-catalyzed reaction was found to involve the isomerization of the exo- to the endo-cycloadduct in the presence of L-proline.ArticleHETEROCYCLES. 81(7):1669-1688 (2010)journal articl

Functionalized coatings by electrospinning for anti-oxidant food packaging

The development of advanced formulations used for food packaging applications, which behave as protection or preservation materials and improve consumers’ health offers a route to reduced food wastage. The present study deals with investigations on the possibility of obtaining functionalized coatings by electrospinning of poly(ɛ-caprolactone), a synthetic biodegradable polymer together with vitamin E (α-tocopherol), selected as plant-based phenolic antioxidant. In this approach electrospinning allows the production of high surface area materials and thus offering an increased antioxidant activity. The electrospun fibres of poly(ɛ-caprolactone)/vitamin E were obtained, studied and their antioxidant properties were evaluated by measuring the fibre reactivity with 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. The potential for extending the shelf-life of food products by using this approach is discussed