A new route to tricyclane sesquiterpenoids: total synthesis of α-ekasantalic acid

YesChemical manipulation of the cycloadduct of citraconic anhydride and cyclopentadiene enables a new synthetic route to tricyclane sesquiterpenoids. This methodology is applied to the first total synthesis of α-ekasantalic acid.Spanish Ministry of Education, Culture and Sport for financial support (grant number TME2011-00267 (LL))

Synthesis and Biological Evaluation of Phenanthrenes as Cytotoxic Agents with Pharmacophore Modeling and ChemGPS-NP Prediction as Topo II Inhibitors

In a structure-activity relationship (SAR) study, 3-methoxy-1,4-phenanthrenequinones, calanquinone A (6a), denbinobin (6b), 5-OAc-calanquinone A (7a) and 5-OAc-denbinobin (7b), have significantly promising cytotoxicity against various human cancer cell lines (IC50 0.08–1.66 µg/mL). Moreover, we also established a superior pharmacophore model for cytotoxicity (r = 0.931) containing three hydrogen bond acceptors (HBA1, HBA2 and HBA3) and one hydrophobic feature (HYD) against MCF-7 breast cancer cell line. The pharmacophore model indicates that HBA3 is an essential feature for the oxygen atom of 5-OH in 6a–b and for the carbonyl group of 5-OCOCH3 in 7a–b, important for their cytotoxic properties. The SAR for moderately active 5a–b (5-OCH3), and highly active 6a–b and 7a–b, are also elaborated in a spatial aspect model. Further rational design and synthesis of new cytotoxic phenanthrene analogs can be implemented via this model. Additionally, employing a ChemGPS-NP based model for cytotoxicity mode of action (MOA) provides support for a preliminary classification of compounds 6a–b as topoisomerase II inhibitors

A new, general method for the synthesis of carbasugar-sugar pseudodisaccharides

A general synthetic methodology for the synthesis of sugar-carbasugar pseudodisaccharides is described. The methodology is based on the cycloaddition of pyran-2-ones to vinylated sugars and the subsequent manipulation of the cycloadducts to construct the carbasugar component of the pseudodisaccharide. © 2009 American Chemical Society

Control of the stereochemistry of C14 hydroxyl during the total synthesis of withanolide E and physachenolide C

The stereochemical outcome of the epoxidation of Δ14–15 cholestanes with mCPBA is controlled by the steric bulk of a C17 substituent. When the C17 is in the β configuration, the epoxide is formed in the α face, whereas if the C17 is trigonal (flat) or the substituent is in the α configuration, the epoxide is formed in the β face. The presence of a hydroxyl substituent at C20 does not influence the stereochemical outcome of the epoxidation.  </p

When Z '=2 is better than Z '=1-supramolecular centrosymmetric hydrogen-bonded dimers in chiral systems

High Z‘ structures can be engineered by combining a molecule with one (or more) resolved chiral center(s) with a strongly directional supramolecular synthon with a preference for centrosymmetry because, in order to preserve the dimer motif, one or more extra molecules must be introduced into the asymmetric unit

Isolation and characterisation of all four diastereomeric intermediates from a horner-wittig reaction

The Horner-Wittig reaction between diphenyl(2-phenylpropyl)phosphine oxide and 1-naphtaldehyde affords an equal mixture of the cis and trans isomers even though the formation of the initial adduct is selective. © 2013 Copyright Taylor and Francis Group, LLC