- Poppy acid: Synthesis and crystal chemistry
-
It had long ago been reported that poppy acid crystals encapsulate and orient a great variety of molecules during solution growth and in so doing seem to egregiously violate the principle of isomorphism. To comprehend this surprising host-guest chemistry, and exploit it for measuring anisotropic molecular properties, we attempted to carry out the oft-used literature synthesis of poppy acid, (3-hydroxy-2,6-dicarboxyγ-pyrone), but discovered that the standard procedures did not produce the title compound. We instead obtained a constitutional isomer as the potassium salt of 2-oxaloate-3- hydroxy-5-carboxyfuran. Therefore, we designed and carried out the first total synthesis of poppy acid. It crystallizes as either of two polymorphs, an orthorhombic form (Pbca) and a monoclinic form (C2/c), both characterized by weakly bonded layers consistent with perfect cleavages. The great majority of the dyes tested, 15 of 19, produced poppy acid crystals colored in particular growth sectors displaying strong linear dichroism. The observation of pronounced absorption anisotropy is consistent with a general mixed crystal growth mechanism in which the dyes substitute for poppy acid molecules within the layers and are further oriented in the direction of hydrogen bound rows of molecules within layers.
- Lovell, Scott,Subramony, Paramjeet,Kahr, Bart
-
-
Read Online
- Synthesis of new kojic acid based unnatural α-amino acid derivatives
-
An efficient method for the preparation of kojic acid based α-amino acid derivatives by alkylation of glycinate schiff base with bromokojic acids have been described. Using this method, mono as well as di alkylated kojic acid-amino acid conjugates have been prepared. This is the first synthesis of C-linked kojic acid-amino acid conjugate where kojic acid is directly linked to amino acid through a C-C bond.
- Balakrishna,Payili, Nagaraju,Yennam, Satyanarayana,Uma Devi,Behera, Manoranjan
-
supporting information
p. 4753 - 4756
(2015/10/28)
-
- Potent antimalarial 4-pyridones with improved physico-chemical properties
-
Antimalarial 4-pyridones are a novel class of inhibitors of the plasmodial mitochondrial electron transport chain targeting Cytochrome bc1 (complex III). In general, the most potent 4-pyridones are lipophilic molecules with poor solubility in aqueous medi
- Bueno, José M.,Manzano, Pilar,García, María C.,Chicharro, Jesús,Puente, Margarita,Lorenzo, Milagros,García, Adolfo,Ferrer, Santiago,Gómez, Rubén M.,Fraile, María T.,Lavandera, José L.,Fiandor, José M.,Vidal, Jaume,Herreros, Esperanza,Gargallo-Viola, Domingo
-
scheme or table
p. 5214 - 5218
(2011/10/02)
-
- Novel heterocyclic compounds
-
4-pyridone derivatives of Formula I and pharmaceutically acceptable derivatives thereof, processes for their preparation, pharmaceutical formulations thereof and their use in chemotherapy of certain parasitic infections such as malaria, are provided.
- -
-
Page/Page column 22-23
(2008/06/13)
-
- Orally active iron (III) chelators
-
A compound of formula I wherein R is hydrogen or a group that is removed by metabolism in vivo to provide the free hydroxy compound, R1is an aliphatic hydrocarbon group or an aliphatic hydrocarbon group substituted by a hydroxy group or a carboxylic acid ester, sulpho acid ester or a C1-6alkoxy, C6-aryloxy or C7-10aralkoxy ether thereof, and R3is selected from hydrogen and C1-6alkyl; characterized in that R2is selected from groups (i) —CONH—R5(ii)—CR6R6OR7(iii) —CONHCOR5and (iv) —CON(CnH2n+1)2 R4is selected from hydrogen, C1-6alkyl and a group as described for R2; R5is selected from hydrogen and optionally hydroxy, alkoxy, aryloxy or aralkoxy substituted C1-13alkyl, aryl and C7-13alkyl R6is independently selected from hydrogen and C1-13alkyl, R7is selected from hydrogen, C1-13alkyl, aryl and C7-13aralkyl or a pharmaceutically acceptable salt of any such compound and CnH2n+1is C1-6alkyl with the proviso that the compound is not one of 1-ethyl-2-(1′-hydroxyethyl)-3-hydroxypyridin-4-one and 1-methyl-2-hydroxymethyl-3-hydroxypyridoin-4-one.
- -
-
-
- Cephalosporin compounds and antibacterial agents
-
Novel cephalosporin compounds represented by formula (I): STR1 wherein R1 represents a lower alkyl group which may optionally have a substituent; each of R2 and R3 independently represents a hydrogen atom or hydroxy group; and A represents a hydrogen atom or a residue of nucleophilic compound, and pharmacologically acceptable salts or esters thereof exhibit a potent antibacterial activity against gram positive and gram negative bacteria.
- -
-
-