Chiral Allenylcarbonyls - Underexploited Building Blocks for Complex Synthesis
Chiral allenylcarbonyls such as allenoates remain underutilized in complex synthesis despite recent advances in synthesis methods to prepare them non-racemically. The field is now ripe for the employment of this class of allenes as building blocks to facilitate the construction of complex small-molecule compounds, such as bridged bicycles.
An Efficient Oxidation of Alcohols by Aqueous HO with 1,3-Dibromo-5,5-Dimethylhydantoin
An efficient protocol is described for the oxidation of alcohols to the corresponding aldehydes or ketones with 1,3-dibromo-5,5-dimethylhydantoin in the presence of aqueous H2O2.
Direct Oxidation of Aldehydes to Methyl Esters with Urea Hydrogen Peroxide and -Toluenesulfonyl Chloride
Combination of urea hydrogen peroxide and p-toluenesulfonyl chloride in methanol was proved to be facile and highly efficient for the oxidative methyl esterification of various aldehydes to the corresponding carboxylic methyl esters.
FledFold: A Novel Software for RNA Secondary Structure Prediction
RNA secondary structure is essential to understand the mechanism of RNAs.
A Short Route to the Ester (±) HomoSarkomycin Johnson-Claisen Rearrangement
α-Methylene cycloalkanones are considered of interest because of their biological activity. Herein, in this paper the synthesis of (±) HomoSarkomycine Esters was described and characterized.
Synthesis of bis(indolyl)methanes Catalyzed by Triethylborane
Triethylborane (TEB) was found to be a mild, efficient, and acid catalyst in electrophilic substitution reaction of indoles with aldehydes compounds to afford the corresponding bis(indolyl)methanes. Vibrindole and bis(indolyl)methanes derivatives and were synthesized using this methodology. Compound is an intermediary in the synthesis of the natural bisindoles arsindoline and streptindole . The structure of vibrindole was unequivocally confirmed by a single crystal X-ray diffraction analysis.
A Novel Semisynthetic Anion Receptor: Synthesis and Ion Recognition of (1-H-pyrrol-2-yl)-4-oxo-perezone
We describe the synthesis of the novel 2-(1,5-dimethyl-4-oxo-hexyl)-3-hydroxy-5-methyl-6-pyrrolyl-1,4-benzoquinone 2 from the natural product perezone 1. The anion-guest properties of the new compound were evaluated in the presence of fluoride, chloride, bromide and iodide tetrabutylammonium salts using 1H NMR titration techniques in deuterated dichloromethane or dimethylformamide. The title compound showed interesting colorimetric behavior in the presence of inorganic salts.
Synthesis and Evaluation of an -Aminated Naphthol AS-E as a Prodrug of CREB-mediated Gene Transcription Inhibition
An -aminated naphthol AS-E was designed as a prodrug to achieve reductive activation and improved aqueous solubility. During the synthesis of this designed compound, a novel transformation from aryl triflates and ethyl acetohydroximate to oxazoles was discovered. Although the initially designed -amino naphthol AS-E was not made successfully, the eventually synthesized --butylamino derivative was found to be biologically inactive, suggesting that reductive cleavage in this compound was not facile due to unfavorable steric and electronic effects.
A Practical Synthesis and X-ray Crystallographic Analysis of Dithymoquinone, a Photodimer of Thymoquinone
An updated and practical approach to the synthesis of dithymoquinone via one-step photoirradiation of thymoquinone (2-methyl-5-isopropyl-1,4-benzoquinone) is described. Synthesis resulted in a 55% yield of one structural isomer ( derivative), as confirmed by HPLC, NMR spectroscopy and first ever single-crystal X-ray diffraction analyses.
Pd/C-Catalyzed Cross-Coupling of Arenediazonium Salts with Potassium Aryltrifluoroborates
A convenient protocol for the synthesis of biaryls from arenediazonium salts and potassium aryltrifluoroborates in refluxing methanol catalyzed by Pd/C is described. The protocol is simple to execute and gives moderate to high yields of cross-coupling products in most cases.
Preparation of Disubstituted Phenyl Propargyl Alcohols, their Use in Oxathiolene Oxide Synthesis, and Evaluation of the Oxathiolene Oxide Products as Anticarcinogenic Enzyme Inducers
A number of alkynols have been prepared by Sonogoshira coupling of propargyl alcohol to disubstituted aromatic halides. Chelation controlled addition of organometallic nucleophiles to these alkynols was then affected followed by the addition of sulfur dioxide. This methodology was used to prepare a number of oxathiolene oxides which have been screened as NQO1 (quinone oxidoreductase) inducers.
Visualization of Hyperconjugation and Subsequent Structural Distortions through 3D Printing of Crystal Structures
Structural distortions due to hyperconjugation in organic molecules, like norbornenes, are well captured through X-ray crystallographic data, but are sometimes difficult to visualize especially for those applying chemical knowledge and are not chemists.
Carbon-Carbon Bond Formation Facilitated by π-Complexed Organometallic Auxiliaries: An Overview
Organometallic moieties attached to substrates via π-complexation play an important role as auxiliaries. As described in the present review, η-linked auxiliaries have been employed to overcome numerous synthesis obstacles that continue to present significant challenges for catalyzed reactions. This has been particularly true in carbon-carbon bond forming reactions involving highly unsaturated systems such as arenes, dienes and allenes, which are emphasized here.
