• Bulletin of the Korean Chemical Society
• /
• 제34권10호
• /
• pp.2963-2967
• /
• 2013

This paper describes a simple and efficient method involving domino Knovenegal/$6{\pi}$ electrocyclization for the preparation of a variety of 2H-pyrans using microwave irradiation under solvent- and catalyst-free conditions. This method offers the advantages of a green approach, high yields, and short reaction times. Sixteen compounds (9a-p) were obtained in good to excellent yields using the procedure.

• Bulletin of the Korean Chemical Society
• /
• 제30권11호
• /
• pp.2833-2836
• /
• 2009

• Bulletin of the Korean Chemical Society
• /
• 제7권5호
• /
• pp.372-376
• /
• 1986

Substituted 3,4-dihydro-2H-pyrans ($1_{a-e}$) were prepared by (4 + 2) cycloaddition reaction of dimethyl dicyanofumarate with the corresponding electron-rich olefins. The compounds $1_{a-e}$ were ring-open polymerized by cationic initiators to obtain polymers of 1:1 alternating sequence. Polymerizations were carried out with boron trifluoride etherate in methylene chloride at $-78^{\circ}C$. All the polymers obtained were soluble in common solvents and were reprecipitated by pouring its chloroform solution into diethyl ether. All the compounds $1_{a-e}$ were not as reactive as the corresponding pyrans derived from ${\alpha}$ -cyanoacrylate.

• Bulletin of the Korean Chemical Society
• /
• 제23권7호
• /
• pp.998-1002
• /
• 2002

An efficient synthesis of 2H-pyrans is achieved by indium (III) chloride-catalyzed reactions of 1,3-dicarbonyl compounds with a variety of $\alpha\beta-unsaturated$, aldehydes in moderate yields. This method has been applied to the synthesis of pyranocoumar ins, pyranophenalenones, and pyranoquinolinone alkaloids.

• Bulletin of the Korean Chemical Society
• /
• 제25권11호
• /
• pp.1733-1736
• /
• 2004

• Bulletin of the Korean Chemical Society
• /
• 제22권8호
• /
• pp.791-792
• /
• 2001

• Bulletin of the Korean Chemical Society
• /
• 제32권2호
• /
• pp.566-570
• /
• 2011

An efficient and general synthesis of bibenzyl derivatives bearing pyranyl rings was achieved by ethylenediamine diacetate-catalyzed reactions of 3,5-dihydroxybibenzyl with ${\alpha},{\beta}$-unsaturated aldehydes in moderate yields. These reactions provided naturally occurring compounds 1 and 2 in single step reaction. As an application of this methodology, biologically interesting natural bauhinol D (8) was synthesized by a convergent sequence from readily available benzaldehyde and benzyl phosphonate.

• 한국산업융합학회 논문집
• /
• 제9권4호
• /
• pp.331-336
• /
• 2006

An efficient synthesis of 3,4-dihydro-2H-pyrans is achieved by $Ag_2CO_3$/celite mediated reaction of 1,3-dicarbonyl compounds with vinyl ether in moderate yields. This method has been applied to the synthesis of 3,4-dihydro-2H-pyranochromens and 3,4-dihydro-2H-benzochromen. 3,4-Dihydro-2H-pyranochromens were easily converted to 4H-pyranochromens by elimination of ethoxy group. The structures of these compound were identified by IR and $^1H$ NMR-Spectra.

• Bulletin of the Korean Chemical Society
• /
• 제31권10호
• /
• pp.2884-2888
• /
• 2010

Two red fluorescent DCJTB derivatives (Red 1 and 2) based on modified pyrans were synthesized and their electroluminescent properties were investigated. Multilayered OLEDs were fabricated with the device structure of ITO/NPB (40 nm)/Red 1, 2 or DCJTB (0.5 or 1%): $Alq_3$ (20 nm)/$Alq_3$ (40 nm)/Liq (2 nm)/Al. All devices exhibited efficient red emissions. In particular, a device containing emitter Red 2 as a dopant in the emitting layer, the maximum luminance was $8737\;cd/m^2$ at 12.0 V, the luminous and power efficiencies were 2.31 cd/A and 1.25 lm/W at $20\;mA/cm^2$, respectively. The peak wavelength of the electroluminescence was 638 nm with the CIE (x,y) coordinates of (0.63, 0.36) at 7.0 V.

• 한국전기전자재료학회논문지
• /
• 제18권10호
• /
• pp.936-940
• /
• 2005

IMML(Inorganic metal multi-layer) was used as cathode in the OLED devices to reduce the reflectance or ITO and increase the contrast ratio. Device structure was $ITO/{\alpha}-NPD/Alq_3:DCJTB/Alq_3/IMML/Al$. $Alq_3$ and DCJTB (4 - (dicyanomethylene) - 2 - ( 1 - propyls) 6 - methy 4H - pyrans) as host material lot red emission and red emitting guest material. IMML made three different layer: thin aluminum layer, aluminum layer doped with silicon monoxide, thick aluminum layer. The red OLED device with IMML showed the average reflectance of $4.97\%$, and then normal OLED with or without polarizer showed the average reflectance of $4.55\%$, $46\%$ at visible range from 380 nm to 780 nm. The brightness of OLED with IMML at 13 V was 5557 $cd/m^2$, and that of normal OLED with polarizer was 4872 $cd/m^2$. IMML could be the substitution for polarizer with same reflection, low cost, easy process in flat panel display market.