Fluorine-containing β-sultones

Russian Chemical Bulletin -     

Fluorine-containing β-sultones

Summary A calculation was made of the group refraction of fluorosulfonyl attached to the carbon atom of an alkyl group; .     

Preparation of β-fluoro- and β,β-difluoro-histidinols

Nucleophilic attack of azide on 2-bromo-3-fluoro-3-(1-trityl-1H-imidazol-4-yl)-propan-1-ol (1a) in aprotic solvent occurs on the 2-position to give the 2-azido derivative (2a). Reduction of azide and removal of the trityl group produces β-fluorohistidinol (6a). Elimination of HBr from 1a followed by “FBr” addition to the resulting double bond gives 2-bromo-3,3-difluoro-3-(1-trityl-1H-imidazol-4-yl)-propan-1-ol (1b). Nucleophilic attack of azide followed by reduction and removal of the trityl group, as for the preparation of 6a, gives β,β-difluorohistidinol (6b). Initial attempts, under a variety of conditions, to oxidize the fluorinated histidinol precursors to carboxylic acids have not been successful.     

Geminally activated β-nitrostyrenes in reactions with cyclic β-diketones

The interaction of gem-benzoylnitroethenes and gem-alkoxycarbonylnitroethenes with cyclic β-diketones (dihydroresorcinol and dimedone) occurs as a one-pot process via sequential Ad_N and S_N steps followed by denitration to give functionally substituted hexahydrobenzofurans. The intermediate products of the nucleophilic addition have been isolated in the reactions of gem-acetylnitroethenes with dihydroresorcinol. The structures of the synthesized compounds have been confirmed by IR, ¹H, and ¹³C-{¹H} spectroscopy including the heteronuclear correlation experiments (¹H-¹³C HMQC and ¹H-¹³C HMBC).     

Practical synthesis of β-acyl and β-alkoxycarbonyl heterocyclic sulfones

A short and efficient synthesis for β-acyl and β-alkoxycarbonyl heterocyclic sulfones containing benzothiazol (BT) and phenyltetrazol (PT) heterocyclic core is presented here. The method seems to be general and provides the desired C-nucleophiles in very good to excellent yields from readily available starting materials.     

A Convenient Synthesis of β-Chloro, β-Methylthio α,β-Unsaturated Ketones from β-Oxodithioesters

The reaction of β-oxodithioesters with the Vilsmeier-Haack reagent prepared from POCl₃ and DMF provide β-chloro, β-methylthio α,β-unsaturated ketones in good yields.     

Amine-promoted β-elimination of a β-aryloxy aldehyde for fluorogenic chemodosimeters

We previously reported a fluorescent chemodosimeter for ozone. The β-elimination step after the ozonolysis of the chemodosimeter was too slow to be practical for real-time monitoring of ozone. We examined primary, secondary, and tertiary amines at various pHs. It was found that pyrrolidine in pH 9 buffer could accelerate the elimination to generate a fluorescence signal. The elimination step is now sufficiently rapid to monitor ozone exposure in real time. We also discovered that azetidine was distinctly effective for the same elimination reaction in a pH 6 buffer.     

Fluorine containing β-lactones

Summary Ring opening of -trifluoromethyl- -methyl- -propiolactone is unidirectional and leads to derivatives of -trifluoromethyl- -hydroxybutyric acid.     

Fluorine containing β-sultones

Summary The reaction between fluorine containing -sultones and mercaptans has been studied and a series of thioesters of substituted fluorosulfonylacetic acids has been obtained.     

Paramagnetic aluminium β-diketiminate

The β-diketiminate ligand framework is shown to undergo reduction to form a neutral main group radical stabilized by spiroconjugation of the unpaired electron over the group 13 element centre. The synthesized paramagnetic complex was characterized by EPR spectroscopy and computational chemistry.     

Tetranuclear copper complexes with new β-diketone and β-iminoketone-containing ligands

Novel tetranuclear copper complexes, Cu4(OH)2(ClO4)3 (HA)·H2O (1) and Cu4(ClO4)5(H3B)·3H2O (2), were synthesized by reacting 1,5-bis(1-phenyl-3-methyl-5-pyrazolone-4)-1 ,5-pentanedione with 1,3-propanediamine and 2-hydroxyl-1,3-propanediamine in the presence of a template reagent copper ion. New [2+2] type open cyclic multidentate ligands are also obtained from the reaction (H4A and H6B stand for new compounds from 1,3-propanediamine and 2-hydroxyl-1,3-propanediamine, respectively). They each contain five C = O, three C = N and one NH2 groups. The complexes were characterized by elemental analyses, conductivity, FT-i.r. (micro-i.r., deconvolution technique), FAB-MS, e.s.r., electronic spectra and extended X-ray absorption fine structure (EXAFS). Copper ions in (1) are basically four coordinate with tetragonal geometry. The average coordination bond distances of Cu–N and Cu–O are 1.91 Å and 2.05 Å. In (2), copper ions are primarily five coordinate with square-based pyramidal geometry. The average coordination bond distances of Cu–N and Cu–O are 1.93Å and 2.08Å. Four copper atoms in molecules may be arranged tetragonally. Both the ligand field and the coordination bonds in complex (1) are stronger than those in (2). Investigations on variable temperature susceptibilities show that some antiferromagnetic exchange interaction exist in the complexes. The plots of –1 versus T obey the Curie-Weiss law only at low temperature. Preliminary results of a bioassay indicate that the two complexes have some antitumour activity in vitro.     

High-yielding oxidation of β-hydroxyketones to β-diketones using o-iodoxybenzoic acid

The oxidation of β-hydroxyketones to β-diketones was systematically investigated. o-Iodoxybenzoic acid (IBX) was found to be efficient, operationally easy, and superior to other common oxidants. The reaction is suitable for milligram- to gram-scale oxidations.     

Chiral monofluorobenzyl carbanions: synthesis of enantiopure β-fluorinated β-phenylethylamines

The preparation of a stabilized monofluorobenzyl carbanion by means of a remote homochiral sulfinyl group and its completely stereoselective reactions with N-p-tolylsulfinylimines are described. The use of these reactions followed by the simultaneous removal of both chiral auxiliaries with tBuLi, which occurs without epimerization at the benzylic position, provides the quickest entry to enantiomerically pure β-fluorinated β-phenylethylamines.     

SYNTHESIS OF β-TRIMETHYLARSONIUMLACTATE

Abstract

The biochemistry of arsenic is of considerable interest owing to the widespread presence of the element in marine organisms.¹ The substance arsenobetaine (Me₃-As⁺CH₂CO₂ ^?) has been isolated from the tail muscle of the western rock lobster (Panulirus longipes cygnus) and from the flesh of the dusky shark (Carcharhinus obscurus) and subsequently characterized by independent synthesis and X-ray crystal structure analysis.² In addition, two arsenic-containing ribose derivatives have been isolated from the brown kelp Ecklonia radiata, which is part of the coastal ecosystem to which the rock lobster belongs.³ Assimilation, reduction, and methylation of arsenate also occurs in photosynthetic marine organisms,^4,5 particularly in phosphate-depleted tropical waters, and in molluscs and ascidians, where arsenic accumulation was found to be greatest in organisms bearing symbiotic algae.⁵ Marine algae cultured in [⁷⁴As] arsenate synthesize an arsenic-containing phospholipid.⁶ Base-catalysed deacylation of the lipid, followed by acid or enzyme hydrolysis of the intermediate phosphodiester, produced a product believed to be the β-trimethylarsoniumlactate, (4). However, a rigorous chemical characterization of the novel zwitterion was not undertaken. Accordingly, we describe here the synthesis of (4), together with some of its properties.