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1.
Nat Chem ; 13(4): 327-334, 2021 04.
Article in English | MEDLINE | ID: mdl-33833448

ABSTRACT

The asymmetric construction of all-carbon quaternary centres within acyclic settings represents a long-standing challenge for synthetic chemists. Alongside polar and radical methods, rearrangement reactions represent an attractive platform, but still broadly applicable methods are in high demand. Here we report an asymmetric, radical sulfinyl-Smiles rearrangement to access acyclic amides that bear an α-all-carbon quaternary centre. Our strategy uses enantioenriched N-arylsulfinyl acrylamides as acceptors for a variety of radicals produced in situ under mild photoredox conditions. The sulfinamido group not only directs the 1,4-migration of the aryl moiety onto the α-carbon of the amide, which thus governs its absolute configuration, but also functions as a traceless chiral auxiliary. The amides obtained in this multicomponent process are prevalent in pharmaceuticals, agrochemicals and bioactive natural products, and can be transformed into valuable chiral α,α-disubstituted acids, oxindoles as well as into ß,ß-disubstituted amines, highlighting the synthetic potential of this transformation.


Subject(s)
Amides/chemical synthesis , Sulfoxides/chemistry , Light , Models, Chemical , Stereoisomerism , Sulfoxides/radiation effects
2.
Photochem Photobiol Sci ; 11(10): 1575-84, 2012 Oct.
Article in English | MEDLINE | ID: mdl-22859061

ABSTRACT

The present study discusses the influence of sunlight on the photostability of levomepromazine (LV) and olanzapine (OLA) hydrochlorides in river water. Four samples of water from different rivers were used in the research. In their course, it turned out that levomepromazine easily underwent photooxidation under simulated environmental conditions, resulting in the generation of its sulphoxide. Olanzapine, on the other hand, appeared to be more resistant to sunlight, as its photodecomposition proceeded slowly, and only one product of its decomposition was detected spectrophotometrically during the process. The photodegradation was analyzed in detail using principal component analysis (PCA) and multivariate curve resolution alternating least squares (MCR-ALS) chemometric methods, and the outcomes verified by HPLC and GC-MS analysis. It can be stated that the rates of the observed processes heavily depended on the chemical composition of the fresh water used in the experiments.


Subject(s)
Benzodiazepines/radiation effects , Methotrimeprazine/radiation effects , Photolysis , Sulfoxides/radiation effects , Sunlight , Water Pollutants, Chemical/radiation effects , Benzodiazepines/chemistry , Chromatography, High Pressure Liquid , Gas Chromatography-Mass Spectrometry , Kinetics , Least-Squares Analysis , Methotrimeprazine/chemistry , Olanzapine , Principal Component Analysis , Rivers/chemistry , Sulfoxides/chemistry , Water Pollutants, Chemical/chemistry
3.
J Phys Chem A ; 112(37): 8723-30, 2008 Sep 18.
Article in English | MEDLINE | ID: mdl-18717539

ABSTRACT

Using relative rate methods, rate constants for the gas-phase reactions of divinyl sulfoxide [CH 2CHS(O)CHCH 2; DVSO] with NO 3 radicals and O 3 have been measured at 296 +/- 2 K, and rate constants for the reaction with OH radicals have been measured over the temperature range of 277-349 K. Rate constants obtained for the NO 3 radical and O 3 reactions at 296 +/- 2 K were (6.1 +/- 1.4) x 10 (-16) and (4.3 +/- 1.0) x 10 (-19) cm (3) molecule (-1) s (-1), respectively. For the OH radical reaction, the temperature-dependent rate expression obtained was k = 4.17 x 10 (-12)e ((858 +/- 141)/ T ) cm (3) molecule (-1) s (-1) with a 298 K rate constant of (7.43 +/- 0.71) x 10 (-11) cm (3) molecule (-1) s (-1), where, in all cases, the errors are two standard deviations and do not include the uncertainties in the rate constants for the reference compounds. Divinyl sulfone was observed as a minor product of both the OH radical and NO 3 radical reactions at 296 +/- 2 K. Using in situ Fourier transform infrared spectroscopy, CO, CO 2, SO 2, HCHO, and divinyl sulfone were observed as products of the OH radical reaction, with molar formation yields of 35 +/- 11, 2.2 +/- 0.8, 33 +/- 4, 54 +/- 6, and 5.4 +/- 0.8%, respectively, in air. For the experimental conditions employed, aerosol formation from the OH radical-initiated reaction of DVSO in the presence of NO was minor, being approximately 1.5%. The data obtained here for DVSO are compared with literature data for the corresponding reactions of dimethyl sulfoxide.


Subject(s)
Hydroxyl Radical/chemistry , Nitrogen Oxides/chemistry , Ozone/chemistry , Sulfoxides/chemistry , Vinyl Compounds/chemistry , Aerosols/chemical synthesis , Aerosols/chemistry , Aerosols/radiation effects , Free Radicals/chemistry , Free Radicals/radiation effects , Gases/chemistry , Gases/radiation effects , Hydroxyl Radical/radiation effects , Kinetics , Light , Nitrogen Oxides/radiation effects , Photolysis , Reproducibility of Results , Spectroscopy, Fourier Transform Infrared/methods , Sulfoxides/radiation effects , Temperature , Vinyl Compounds/radiation effects
4.
Bioorg Med Chem Lett ; 17(22): 6116-8, 2007 Nov 15.
Article in English | MEDLINE | ID: mdl-17904368

ABSTRACT

Aryl sulfoxides have been identified as a class of organic compounds capable of inducing DNA cleavage in the presence of UV light. Phenyl sulfoxide and methyl phenyl sulfoxide were both shown to cleave pBR322 DNA at concentrations of 180 and 360 microM, respectively. Radical trapping studies indicate carbon-centered radicals are the active cleavage species.


Subject(s)
DNA Cleavage/radiation effects , Photolysis , Sulfoxides/chemistry , Sulfoxides/radiation effects , Ultraviolet Rays , Benzene Derivatives/chemistry , Benzene Derivatives/radiation effects , Free Radicals/chemical synthesis , Free Radicals/chemistry , Molecular Structure
5.
Inorg Chem ; 45(10): 4024-34, 2006 May 15.
Article in English | MEDLINE | ID: mdl-16676963

ABSTRACT

A dissymmetric 1,10-phenanthroline chelate (N-phen-S) bearing two polyether chains terminated by two monodentate ligands of the benzonitrile (N) and dialkylesulfoxide (S) types was synthesized, characterized, and coordinated to ruthenium. The corresponding Ru(terpy)(N-phen-S)2+ complexes (terpy = 4'-(3,5-ditertiobutylphenyl)-2,2';6',2' '-terpyridine) were fully characterized as being two coordination isomers of the scorpionate type with one of the two tails occupying the sixth position on the coordination sphere. Photoexpulsion of the coordinated tail led to opening of the ruthena-macrocycle and subsequent rearrangement of the bidentate chelate. This rearrangement consisted of a 90 degrees rotation of the phenanthroline around the ruthenium atom. Selective irradiation of one isomer in a mixture of the two was undertaken using band-pass filters; this resulted in an enrichment of the nonirradiated isomer in the mixture. Thermal back-coordination of the tail was investigated in the dark. It took place quantitatively from the corresponding ruthenium chloride complex by trapping of the anion with silver salts.


Subject(s)
Nitriles/chemistry , Organometallic Compounds/chemical synthesis , Phenanthrolines/chemistry , Ruthenium/chemistry , Sulfoxides/chemistry , Ligands , Light , Molecular Structure , Nitriles/radiation effects , Organometallic Compounds/chemistry , Organometallic Compounds/radiation effects , Phenanthrolines/radiation effects , Photochemistry , Stereoisomerism , Sulfoxides/radiation effects , Temperature
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