Synthesis of Fluoroalkylated Heterocycles via the Reaction of 3-（1-Hydropolyfluoroalkenyl）-l-oxo-2,4,1-benzoxazines with Dinucleophilic Reagents

The reaction of 3-（1-hydropolyfluoroalkenyl）-1-oxo-2,4,1-benzoxazines 1 with some dinucleophiles was investigated. 7-Fluoroalkyl-2,3-dihydro- 1,4-diazepine[ 1,2-d]quinazolin- 11-ones 2, 2-fluoroalkylisoxazolo[3,2-b]quinazolin-9-ones 3 and 2-fluoroalkylbenzoimidazoles 4 were obtained from the reaction of 1 with 1,2-diaminoethane, hydroxylamine hydrochloride and 1,2-diaminobenzene respectively.     

Dibenzothiepins, phthalans and phthalides from 4-heterosubstituted dibenzothiins

The lithiation of 4-heterosubstituted dibenzothiins 1 (phenoxathiin, phenothiazine and thianthrene) with lithium and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB, 7.5% molar) in THF at temperatures ranging from −90 to −78°C gives the corresponding functionalised organolithium intermediate I, which by reaction with different electrophiles [H₂O, D₂O, Bu^tCHO, PhCHO, Ph(CH₂)₂CHO, Me₂CO, Et₂CO, (CH₂)₅CO, (CH₂)₇CO] at the same temperature, followed by hydrolysis, gives the expected functionalised thiols 2. Cyclisation of some thiols 2 under acidic conditions leads to the corresponding seven-membered dibenzo heterocycles 5. In the case of thianthrene 1c, after addition of a carbonyl compound as the first electrophile [MeCHO, Bu^tCHO, Me₂CO, Et₂CO, (CH₂)₅CO], the corresponding intermediate II can be lithiated again and react with a second electrophile. Diols 3 are obtained after hydrolysis when a carbonyl compound [Bu^tCHO, PhCHO, Ph(CH₂)₂CHO, Me₂CO, Et₂CO, (CH₂)₅CO] is used as the second electrophile. Acidic cyclisation of diols 3 gives substituted phthalans 6 in almost quantitative yields. Finally, in the case of using carbon dioxide as the second electrophile, phthalides 4 are obtained after acidic hydrolysis.     

Crystal Structure of 1,3-Dibenzyl-2-benzylaminothiocarbonyl-1,3,4- diazaphospholidin-5-thione-4-sulfide

1 INTRODUCTION Lawesson抯 reagent, 2,4-bis(4-methoxyphenyl)- 1,3,2,4-dithiadiphosphetane-2,4-disulfide, can react with certain substrates to give phosphorus heterocycle compounds. These compounds have some potential biological activities as herbicides, fungicides and insecticides[1,2]. By refluxing the Lawesson抯 reagent with benzylisonitrile in benzene, the title compound, 1,3-dibenzyl-2- benzylaminothio- carbonyl-1,3,4-diazaphospholidin-5-thione-4-sulfide was obtained. In the previous …     

On the electronic structure of ethidium

The electronic structure of the common intercalating agent ethidium bromide (3,8-diamino-5-ethyl-6-phenylphenanthridinium bromide) is dominated by an interplay of electron donating and withdrawing effects mediated by its nitrogen atoms. X-ray crystallography, UV/Vis and IR absorption, fluorescence emission, and NMR spectroscopy are used to probe the electronic properties of the phenanthridinium "core" of ethidium as well as its exocyclic amines and 6-phenyl groups. Interestingly, despite its positive charge, most of ethidium's aromatic carbon and hydrogen atoms have high electron densities (compared to both 6-phenylphenanthridine and benzene). The data suggest that electron donation by ethidium's exocyclic amines dominates over the electron withdrawing effects of its endocyclic iminium in their combined influence on the electron densities of these atoms. Ethidium's nitrogen atoms are, conversely, electron deficient where the 5-position is the most electropositive, followed by the 3-amino, and lastly the 8-amino group. These results have been used to generate an empirically-based pi-electron density map of ethidium that may prove useful to understanding its nucleic acid binding specificity.     

A Convenient Palladium‐Catalyzed Carbonylative Synthesis of Benzofuran‐2(3 H)‐ones with Formic Acid as the CO Source

A general and convenient palladium‐catalyzed carbonylation procedure for the synthesis of benzofuran‐2(3 H)‐ones from phenols and aldehydes has been developed. With formic acid as the CO source, a variety of benzofuran‐2(3 H)‐ones were obtained in moderate to good yields.     

Zinc cation supported on carrageenan magnetic nanoparticles: A novel,green and efficient catalytic system for one‐pot three‐component synthesis of quinoline derivatives

This is the first report of supporting zinc cation on ƛ‐carrageenan/Fe₃O₄ magnetic nanoparticles. The structural and magnetic properties of this hybrid (Zn²⁺/ƛ‐carrageenan/Fe₃O₄ nanoparticles) were identified using various techniques. This green and efficient catalytic system was applied in the synthesis of biologically important quinolines. The products were obtained in good to high yields (52–95%) from a one‐pot reaction procedure involving aromatic aldehydes, enolizable aldehydes and aniline derivatives. Our method has many advantages such as mild reaction conditions, easy work‐up, use of a reusable magnetic catalyst and high yields of products.     

STUDIES ABOUT SYNTHESIS,CHARACTERIZATION, AND THE EFFECT OF 2-n-PROPYL-3-ETHYL-3-METHYL-1,4,2-BENZOXAZA-PHOSPHORINE-2-OXIDE ON GROWTH PARAMETERS AND CHLOROPHYLL CONTENT OF WHEAT

This article presents the synthesis and characterization of a new phosphorus heterocycle, namely 2-n-propyl-3-ethyl-3-methyl-1,4,2-benzoxaza-phosphorine-2-oxide, by a Mannich-type reaction between n-propyl-dichlorophosphine, methyl ethyl ketone, and o-aminophenol.

Taking into consideration that chlorophyll contents in plants were revealed to have connection with nitrogen and phosphorus concentrations at early growth stage, and because the above-mentioned heterocyclic compound can be considered as a phosphonic analogous of naturally occuring α-aminoacids, it was expected to develop biological activity from it. That is the reason why 2-n-propyl-3-ethyl-3-methyl-1,4,2-benzoxaza-phosphorine-2-oxide was subjected for biological tests on wheat.

The present study was also undertaken to investigate the interrelationship between chlorophyll content, dry matter, and other growth parameters of wheat, after treatment with different concentrations of 2-n-propyl-3-ethyl-3-methyl-1,4,2-benzoxaza-phosphorine-2-oxide.     

Convenient Synthesis of 3,5‐Disubstituted Isoxazoles

α,β‐Unsaturated oximes obtained from the corresponding α,β‐unsaturated ketones on treatment with 2 equivalents of manganese dioxide in refluxing chloroform gives 3,5‐disubstituted isoxazoles in good yields.     

Synthesis and cytotoxic evaluation of cis-locked and constrained analogues of combretastatin and combretastatin A4

A series of cis-locked stilbenic compounds related to combretastatin and combretastatin A4 has been designed and synthesized. The cytotoxic effects of these rigid analogues were evaluated as well as their abilities to inhibit tubulin polymerization.     

Facile Construction of Medium-Sized Carbocycles,Total Synthesis of (±)-Parvifoline

Abstract

A new synthetic approach to medium-sized rings has been accomplished via intramolecular cyclization of a sulfone-stabilized carbanion. This strategy was applied to the total synthesis of (±)-parvifoline.