Synthetic studies directed toward amphidinol 2: elucidation of the relative configuration of the C1–C10 fragment

Model compounds (11 and 12) for the C1–C10 tetrahydropyran fragment of amphidinol 2 were prepared from (2S)-benzyloxypropanal in 9 steps. The synthetic route relied on diastereoselective diene-aldehyde cycloaddition, stereoselective C-allylation, and reagent based enantioselective aldehyde allylation. Comparison of the NMR spectra for models 11 and 12 with that for amphidinol 2 indicated that the C1–C10 segment of the natural product possesses the 2R*,4R*,6R*,7S*,8R*,10S* relative configuration

Validated Stability Indicating RP-HPLC Method for Simultaneous Estimation of Codeine Phosphate and Chlorpheniramine Maleate from Their Combined Liquid Dosage Form

The present paper describes the development of quick stability indicating RP-HPLC method for the simultaneous estimation of codeine phosphate and chlorpheniramine maleate in the presence of its degradation products, generated from forced degradation studies. The developed method separates codeine phosphate and chlorpheniramine maleate in impurities/degradation products. Codeine phosphate and chlorpheniramine maleate and their combination drug product were exposed to acid, base, oxidation, dry heat, and photolytic stress conditions, and the stressed samples were analysed by proposed method. The proposed HPLC method utilizes the Shimadzu HPLC system on a Phenomenex C18 column (, 5 μ) using a mixture of 1% o-phosphoric acid in water : acetonitrile : methanol (78 : 10 : 12) mobile phase with pH adjusted to 3.0 in an isocratic elution mode at a flow rate of 1 mL/min, at 23°C with a load of 20 μL. The detection was carried out at 254 nm. The retention time of codeine phosphate and chlorpheniramine maleate was found to be around 3.47 min and 9.45 min, respectively. The method has been validated with respect to linearity, robustness, precision, accuracy, limit of detection (LOD), and limit of quantification (LOQ). The developed validated stability indicating HPLC method was found to be simple, accurate, and reproducible for the determination of instability of these drugs in bulk and commercial products

Differing modes of crown binding to potassium: K, 18-crown-6 salt of the cyclic phosphate (OCH₂CMe₂CH₂O)P(O)(OH) as a hydrate

1061-1063The molecular structure of [K,18-crown-6]+[(OCH2CMe2CH2O)P(O2)]-.H2O (3) has been determined. Potassium is eight coordinate and is connected to an oxygen of the phosphate (that is not part of the six-membered ring), the water oxygen and six oxygen atoms of the crown. The two non-crown oxygens coordinated to potassium are on the same side with respect to the mean plane of the crown oxygen atoms; this mode of coordination is different from that observed in [K,18-crown-6]+[myo-C6H6-2-{OC(O)Ph}-1,3,5-(O3CH)-{4,6-O2P(O)O}]-.3H2O (2) in which the coordination of the non-crown oxygens (an oxygen from the inositol residue and an oxygen from the phosphate) occurs from the opposite sides of the mean plane of the crown oxygen atoms. The water oxygen is hydrogen bonded to two oxygen atoms (that are not part of the six-membered ring) of the phosphate leading to a chain. The six-membered phosphorinane ring has a chair conformation

Synthesis and structural characterization of a new class of macrocycles based on a cyclodiphosphazane skeleton

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Synthesis and structure of the macrocycle [(OCH₂CEt₂CH₂O) {P(N-<i>t</i>-Bu)₂P}]₂

2371-2375The compound [(OCH2CEt2CH2O){P(N-t-Bu)2P}]2 (7) has been synthesized by the reaction of the cyclodiphosphazane [ClPN-t-Bu]2 (1) with an equimolar quantity of 2,2-diethyl-1 ,3-propanediol. An X-ray structure determination confirms that it is a l6-membered macrocycle. This mode of reaction is compared with those of 1 with various other difunctional amines/alcohols where only monomeric (in cyclodiphosphazane units) compounds are isolated. Reaction of 1 with half mole equivalents of the diols HOCH2CR2CH2OH [R = H, Me, Et] afforded products formulated as (OCH2CR2CH2O){P(N-t-Bu)2 PCl}2. Attempts to incorporate lithium ion into 7 and the related methyl compound [(OCH2CMe2CH2O){P(N-t Bu)2P}]2 (4) have not been successful

Diverse Modes of Reactivity of Dialkyl Azodicarboxylates with P(III) Compounds: Synthesis, Structure, and Reactivity of Products Other than the Morrison-Brunn-Huisgen Intermediate in A Mitsunobu-Type Reaction

10.1021/jo035634dJournal of Organic Chemistry6961880-1889JOCE