Abstract Regio- and stereoselective methods for the synthesis of 6′-trifluoro(trichloro)methyl substituted spiro[acenaphthylene-1,11′-chromeno[3,4-a](thia)pyrrolizidin]-2-ones spiro[acenaphthylene-1,12′-chromeno[3,4-a]indolizidin]-2-ones have been developed based on three-component reaction 3-nitro-2-trifluoro(trichloro)methyl-2H-chromenes with azomethine ylides generated in situ from acenaphth...

in this study, the synthesis of 4 h -chromenes of biological activity via a multicomponent reaction of dimedone, aromatic aldehydes and malononitrile catalyzed by glutamic acid as a catalyst was investigated. the structural features of the synthesized compounds were characterized by melting point, ir and 1 h nmr analysis. the catalyst being reported here is cheap, safe to handle and the whole p...

In this study, we reported facile and efficient synthesis of 2-amino-4H-chromenes that catalyzed by polystyrene-supported 1-methylimidazolium tetrachloroferrateas. The synthesis proceeds with various aldehydes under mild conditions and afford the target products with good to high yields.

A facile and efficient one-pot, multicomponent synthesis of 4H-chromenes is reported, through the reaction of arylglyoxalmonohydrates with 1,3-diketones and malononitrile in eTEMPthanol in the presence of L-proline as a catalyst.

Gaussian scale space permits one to compute image derivatives. The limitation to some finite order is not inherent in the paradigm itself (Gaussian blurred functions are always smooth), but is caused by the interplay of (at least) two external factors. One is the ratio of the Gaussian scale parameter versus the atomic scale that limits physically or perceptually meaningful sizes (e.g. pixel siz...

Two studies were performed to evaluate the effects of dried distillers grains with solubles (DDGS) on the lactational performance of dairy cows. The intent of experiment 1 was to evaluate the effects of feeding increasing concentrations of DDGS on the feed intake and production of Holstein dairy cows. Twenty multiparous Holstein cows averaging 76 +/- 24 d in milk and 638 +/- 68 kg of body weigh...

The title compound, C17H27O8P, was prepared by Michaelis-Arbuzov reaction of ethyl 2-bromo-2-(2,3,4-tri-meth-oxy-phen-yl)acetate and triethyl phosphite. Such compounds rarely crystallize, but single crystals were recovered after the initial oil was left for approximately 10 years. The bond angle of the sp (3)-hybridized C atom connecting the benzene derivative with the phospho unit is widened m...

Many metals or their complexes can catalyze the cyclotrimerization of alkynes to give benzene derivatives.1-9 Among these catalysts, palladium chloride10 and its bis(benzonitrile) complex11 are the most convenient. In these reactions, the yields of benzene derivatives generally depend on the substituents of alkynes. In the past 50 years, the regioand chemoselectivity for the cyclotrimerization ...