Two new xanthones, 6-hydroxy-3,7-dimethoxy-8-(3-methylbut-2-enyl)-6',6'-dimethyl-5'-hydroxy-4',5'-dihydropyrano(2',3':1,2)xanthone (1) and 6-hydroxy-3,7-dimethoxy-8-(2-oxo-3-methylbut-3-enyl)-6',6'-dimethyl-5'-hydroxy-4',5'-dihydropyrano(2',3':1,2)xanthone (2), have been isolated from the stems of Cratoxylum cochinchinense (Lour.) Blume. Their structures were established on the basis of spectro...

Two new prenylchalcones, xanthohumol C and D, together with two known prenylchalcone derivatives, xanthohumol (1) and 5''-(2''-hydroxyisopropyl)-dihydrofurano-[2'',3''-b]-4,4'-dihydroxy-6'-methoxy-chalcone (4) were isolated and identified from the hops of Humulus lupulus L. The structures of xanhohumol C and D were elucidated as 5''-hydroxy-6'',6''-dimethyl-dihydropyrano-[2'',3''-b]-4,4'-dihydr...

Highly optically pure multisubstituted dihydropyrano[2,3-c]pyrazol-6-(1H)-ones were synthesized via the N-heterocyclic carbene-catalyzed enantioselective [4 + 2] annulation of α-chloroaldehydes and pyrazolone-derived oxodienes.

7-O-Methyl-luteone was metabolized in a buffer solution by resting cells of Botrytis cinerea which is known as a fungus detoxifying prenylated isoflavones into further oxygenated meta­ bolites, and we could isolate an unstable epoxy-intermediate. The epoxy-intermediate was easily cyclized under acidic conditions to yield the corresponding isoflavone with a hydroxychroman part structure (= dihyd...

An efficient grinding protocol for the synthesis of dihydropyrano[2,3-c]pyrazole derivatives from acetylene ester, hydrazine hydrate, aryl aldehydes and malononitrile under solvent free conditions has been achieved with excellent yields. The structures of the synthesized compounds were deduced by spectroscopic techniques and the compounds were further evaluated for their in vitro antioxidant an...

As a part of systematic investigation of the synthesis and biological activities of pyrazole analogues linked to various heterocyclic systems, a new series of pyrazolo-N-glycoside derivatives, pyrazolopyranopyrimidine and C-glycoside of pyrazolopyranotriazolo-pyrimidine derivatives was synthesized through the reaction of the key intermediate 6-amino-3-methyl-4-(substituted-phenyl)-1,4-dihydropy...

Organocatalyzed synthesis of tert-butyl 2-amino-3-cyano-5-oxo-4-phenyl-5,7-dihydropyrano[2,3-c]pyrrole-6(4H)-carboxylate, prepared from Boc-tetramic acid and benzylidenemalononitrile, is disclosed. Two bifunctional noncovalent organocatalysts were employed, yielding the product as a racemic mixture in both cases. The structure new synthesized compound was confirmed by high resolution mass-spect...

A rapid, clean, and highly efficient method for synthesis of dihydropyrano[3,2-c]chromene derivatives by one-pot, three-component condensation of aromatic aldehydes, malononitrile, and 4-hydroxycoumarin using DABCO as catalyst in solvent-free neat conditions is described. The present method has the advantages of mild reaction conditions, short reaction times, easy isolation of products, and exc...

The prenylated flavonoids, topazolin [5,7,4'-trihydroxy-3-methoxy-6-(3,3-dimethylaIlyl)flavone], piscerythrone [5,7,2',4'-tetrahydroxy-5'-methoxy-3'-(3,3-dimethylallyl)isoflavone] and piscidone [5,7,4',5'-tetrahydroxy-2'-methoxy-6'-(3,3-dimethylallyl)isoflavone] were meta­ bolized by Aspergillus flavus and Botrytis cinerea to give a variety of products. Topazolin and piscerythrone were converte...

Two efficient and convenient procedures for the synthesis of 6-amino-3-methyl-1,4-diphenyl-1,4-dihydropyrano[2,3c]pyrazole-5-carbonitrile derivatives based on four-component reaction involving ethyl acetoacetate, phenylhydrazine, malononitrile, and various aromatic aldehydes using trichloroacetic acid or ceric sulfate as heterogeneous catalysts in excellent yields and short reaction times have ...