Free-radical reactions of 2-ethoxy-1,3-oxathiolane

Homolytic reactions of 2-ethoxy-1,3-oxathiolane in the presence of benzoyl peroxide and tert-butyl peroxide in chlorobenzene have been studied. The principal reaction products are diethyl monothiocarbonate and 1,3-oxathiolane-2-one. The yields and ratios of the products are temperature-dependent.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 919–920, July, 1985.     

Radical reduction of cyclic xanthates: Formation of alkenes and/or 1,3-oxathiolanes from 1,3-oxathiolane-2-thiones

AIBN-initiated radical reactions of 5-membered cyclic xanthates, 1,3-oxathiolane-2-thiones, with tributyltin hydride are described. Alkenes are formed at 0.025 M concentration of tributyltin hydride, whereas a higher concentration (0.25 M) gives 1,3-oxathiolanes. A mixture of alkene and 1,3-oxathiolane is obtained by use of intermediate concentrations. Reactions of cis-and trans-4,5-dialkyl-1,3-oxathiolane-2-thiones with tributyltin hydride afford E-alkenes stereoselectively. For an application of this alkene formation reaction, geraniol has been converted to linalool silyl ether in good yield.     

Synthesis of the 1,3-oxathiolanes using asymmetrically oxiranes

An efficient synthesis of 1,3-oxathiolane-2-imin derivatives is described via one-pot reaction between arylisothiocyanats, asymmetrically substituted oxiranes and catalytic amount of methanol.The mild reaction conditions and high yields of the products exhibit the good synthetic advantage of this method.     

Konformations-Gleichgewichte von 1,3-Oxathian-3-Imiden

Two 1,3-oxathiane-3-imides and 1,3-oxathiolane-3-p-chlorophenyl-imide have been prepared. The conformational equilibria of 1,3-oxathiane-3-oxide and of the two 1,3-oxathiane-3-imides have been determined by low temperature¹³C-NMR spectroscopy and compared to data obtained previously² for other cyclic sulfimides.

Herrn Prof. Dr.Karl Schlögl zum 60. Geburtstag gewidmet.     

The methoxycarbonylcarbene insertion into 1,3-dithiolane and 1,3-oxathiolane rings

Treatment of substituted 1,3-dithiolanes and 1,3-oxathiolanes with methyl diazoacetate in the presence of Rh₂(OAc)₄ effects ring expansion to the corresponding substituted 1,4-dithiane-2-carboxylates and 1,4-oxathiane-3-carboxylates. The sulfur ylides initially generated in these reactions undergo Stevens rearrangement in competition with both [2,3]-C-C-sigmatropic rearrangement and intramolecular fragmentation. In the case of 2-styryl-substituted 1,3-oxathiolane and 1,3-dithiolane, ring expansion on one-, three- and four-carbons subsequently takes place.     

Homolytic addition of 1,3-oxathiolane to unsaturated hydrocarbons

The homolytic addition of 1,3-oxathiolane to olefins takes place with the formation of 2-substituted 1,3-oxathiolanes and insignificant amounts of functional derivatives of sulfides.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 259–263, February, 1986.     

Iodomethylethers from 1,3-dioxolane and 1,3-oxathiolane: preparation of acyclic nucleoside analogs

Purine and pyrimidine anions were alkylated using the iodomethyl ether and thioether generated $\text{in}$$\text{situ}$ by the reaction of 1,3-dioxolane and 1,3-oxathiolane with trimethylsilyl iodide.     

Synthesis of S-(2-thioxo-1,3-dithiolan-4-yl)methyl dialkylcarbamothioate and S-thiiran-2-ylmethyl dialkylcarbamothioate via intermolecular O-S rearrangement in water

A facile synthesis of S-(2-thioxo-1,3-dithiolan-4-yl)methyl dialkylcarbamothioates (3) and S-thiiran-2-ylmethyl dialkylcarbamothioate (5) has been reported by the reaction of 5-(chloromethyl)-1,3-oxathiolane-2-thione (1) with sodium dialkylcarbamodithioate (2) and dialkylamine (4), respectively, through intermolecular O-S rearrangement in water. A plausible mechanism of formation of the title compounds has also been proposed.     

Synthesis of positively charged lipids containing a 1,3-oxathiolane cycle

Positively charged lipids of the 1,3-oxathiolane series were synthesized by interaction of 2-pentadecyl-5-tosyloxymethyl- or -5-iodomethyl-1,3-oxathiolane with 2-(N,N-dimcthyl-amino)ethanol.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2347–2349, September, 1996.     

Ionization and dissociation of cyclic ethers and thioethers by electron-impact. A comparison between 1,3-dioxolane, 1,3-dithiolane and 1,3-oxathiolane

The various modes of fragmentation of 1,3-dithiolane and 1,3-oxathiolane under electron-impact have been discussed on the basis of the variation of their mass spectra with electron energy, the high resolution analysis and the AP's of the main ions. They are shown to be similar in both compounds, but considerably different from those of 1,3 dioxolane. From the AP of the [C₂H₅S]⁺ ion in 1,3-dithiolane, a heat of formation of 63 kcal/mol for the free radical CHS is obtained.     

Stereoselective preparation of trifluoromethyl containing 1,4-oxathiolane derivatives through ring expansion reaction of 1,3-oxathiolanes

Trifluoromethyl containing 1,4-oxathiolanes are synthesized in excellent yields and high stereoselectivities from the expansion reactions of sulfur ylide intermediates, which were prepared from the reaction of 2-diazo-3,3,3-trifluoro-propionic acid methyl ester and 1,3-oxathiolanes in the presence of Rh₂(OAc)₄.     

The ring-opening of an unsymmetrical tetrahedral intermediate - 2-hydroxy-1,3-oxathiolane

Ab initio calculations were performed on 2-hydroxy-1,3-oxathiolane: and the two products of its breakdown: Complete geometry optimizations were performed at minimal (STO-3G) and split-valence (3-21G) basis set levels. In addition, a single point calculation was performed at 6-31G* level withd orbitals added on sulfur only. The conformation of the oxathiolane intermediate and its stability relative to the breakdown products was investigated. The STO-3G basis set gave an envelope form while 3-21G gave the twist form of the five-membered ring as the most stable. For all three basis sets the ester product was more stable than thioester.     

Synthesis of Tri-O-acetyl-d-allal from Levoglucosenone

Tri-O-acetyl-d-allal has been enantiospecifically synthesized in six steps from levoglucosenone in 55% overall yield. A key step in the synthesis is the anhydro bridge ring-opening with concomitant formation of a 1,3-oxathiolane-2-thione ring.     

Synthesis and reaction of polymers bearing 5-membered cyclic dithiocarbonate group

5-(Methacryloyloxy)methyl-1,3-oxathiolane-2-thione ( 3 ) was synthesized from glycidyl methacrylate (GMA) and carbon disulfide in the presence of lithium bromide in 93% yield. The radical polymerization of 3 in DMSO initiated by AIBN at 60°C afforded corresponding polymethacrylate 4 quantitatively. Copolymerization of 3 with MMA was also carried out. 5-Phenoxymethyl-1,3-oxathiolane-2-thione ( 6 ), model dithiocarbonate, reacts with benzylamine at room temperature to afford O-(1-mercapto-3-phenoxy-2-propyl)N-benzyl-thiocarbamate ( 7 ) and 1,1′-dithiobis[3-phenoxy-2-(benzylaminothiocarbonyloxy)-propane] ( 8 ) in 89% and 7% yield, respectively. Polymer 4 reacted with butylamine or dipropylamine to afford a corresponding polymethacrylate bearing thiol group, which immediately turned to insoluble gel by facile auto-oxidation of the thiol group. © 1995 John Wiley & Sons, Inc.     

Reactions of aromatic ketones with 3-mercapto-1,2-propanediol. Synthesis of cis- and trans-2-alkyl-2-aryl-(1,3-oxathiolane-5-methanols and 1,3-dioxolane-4-methanethiols)

Aromatic ketones react with 3-mercapto-1,2-propanediol ( 1 ) in refluxing benzene under the catalytic influence of a sulfonic acid and with azeotropic removal of water to yield a mixture comprised predominantly of cis- and trans-2-alkyl-2-aryl-1,3-oxathiolane-5-methanols 7, accompanied by lesser amounts of cis- and trans-2-alkyl-2-aryl-1,3-dioxolane-4-methanethiols 8 (up to 30%). It was discovered that 8 is the kinetic product and is isomerized by 4-toluenesulfonic acid in hot benzene to the thermodynamically more stable 7 . Under these conditions, ortho- and α-substituted aromatic ketones tend to produce more of 8 , which can be attributed to steric hindrance encountered by the thiol as it attacks the ketone. Ketalizations of 1-aryl-2-(1H-imidazol-1-yl)-1- as well as 1-aryl-2-(1,H-1,2,4-triazol-1-yl)-1-ethanones by 1 fail under these conditions, even after 24 hours of reflux in toluene. However, 1-(4-chlorophenyl)-3-(1H-imidazol-1-yl)-1-propanone and 1-(4-bromophenyl)-4-(1H-imidazol-1-yl)-1-butanone are ketalized by 1 as expected. Interestingly, the reaction of 2-bromo-4′-chloroace-tophenone with 1 produces 1-(4-chlorophenyl)-2,8-dioxa-6-thiabicyclo[3.2.1]octane. Characterization of all isomers and separation of some diastereomers is described. Nuclear Overhauser enhancement experiments are utilized to establish the stereochemistry of 1,3-oxathiolanes.     

Chromatographische Verfahren zur Bestimmung von 1, 3-Propansulton (1,2-Oxathiolan-2,2-dioxid) in Luft am Arbeitsplatz

Zusammenfassung Chromatographische Verfahren zur Bestimmung von 1,3-Propansulton (1,2-Oxathiolan-2,2-dioxid) in Luft am Arbeitsplatz werden beschrieben. Die Anwendung einer mit Methyl-i-butylketon beschickten Absorberflasche ermöglicht eine quantitative Anreicherung der genannten Verbindung aus Luft. Durch Kombination von gaschromatographischer Trennung und schwefelselektiver Detektion wird das sorbierte 1,3-Propansulton und damit dessen über die Probenahmedauer gemittelte Konzentration bestimmt. Eine alternative Probenahmetechnik basiert auf der Diffusionsabscheidung von 1,3-Propansulton. Die Probeluft wird hierbei durch ein mit 2-Mercaptobenzthiazol (Na-Salz) beschichtetes Diffusionstrennrohr (Denuder) geleitet, wobei sich 1,3-Propansulton als Na-Salz der 2-Mercaptobenzthiazol-S-propansulfonsäure abscheidet. Nach Beendigung der Probenahme wird das Sulfonat extrahiert und durch HPLC mit UV-Detektion bestimmt.

---

Chromatographic procedures for the determination of 1,3-propanesultone (1,2-oxathiolane-2,2-dioxide) in workplace atmosphere

Summary Chromatographic procedures for the determination of 1,3-propanesultone (1,2-oxathiolane-2,2-dioxide) in workplace atmosphere are described. Quantitative extraction of this compound from air is achieved by employing a washbottle containing methyl-i-butylketone as an absorbent. The amount of preconcentrated 1,3-propanesultone is determined by combination of gas-chromatography with sulfur selective detection. The result obtained is used to calculate the concentration of the species in workplace air averaged for the period of sampling. Alternatively, 1,3-propanesultone can be collected by employing diffusional deposition. In this case the air under investigation is drawn through a diffusion denuder, the inner wall of which is coated with 2-mercaptobenzothiazole (sodium salt) as a sink. By this means 1,3-propanesultone is preconcentrated in the form of the sodium salt of 2-mercaptobenzothiazole-S-propanesulfonic acid. After sampling the denuder is extracted and the sulfonate determined by HPLC with UV detection.

---

---

Herrn Prof. Dr. H. Hartkamp zum 60. Geburtstag gewidmet     

Analysis of the 1H n.m.r. spectrum of 4-methyl-1,3-oxathiolane. An interestingly coupled ABXM3-case

The 220 MHz proton magnetic resonance spectrum of 4-methyl-1,3-oxathiolane was recorded and analysed. The methyl and ethanic protons form an ABXM₃ system, the analysis of which was carried out through several ‘trial-and-error’ attempts. This part of the spectrum is an interesting example of second-order effects which, in the past, have been mistakenly associated with ‘virtual coupling’. The results are compared with those presented earlier for several alkyl substituted 4-methyl-1,3-oxathiolanes.     

1,3-Dimethoxy-1,3-dimethyl-1,3-diphenyl- and 1,3-dimethoxy-1,3-tetraphenyldisiloxanes: synthesis and structure

Russian Chemical Bulletin - 1,3-Dimethoxy- 1,3-dimethyl- 1,3-diphenyl- and 1,3-dimethoxy- 1,3-tetraphenyldisiloxanes were synthesized. Their structures were confirmed by IR and NMR spectroscopy....     

Stereocontrolled 1,3-phosphatyloxy and 1,3-halogen migration relay toward highly functionalized 1,3-dienes

A double migratory cascade reaction of α-halogen-substituted propargylic phosphates to produce highly functionalized 1,3-dienes has been developed. This transformation features 1,3-phosphatyloxy group migration followed by 1,3-shifts of bromine and chlorine as well as the unprecedented 1,3-migration of iodine. The reaction is stereodivergent: (Z)-1,3-dienes are formed in the presence of a copper catalyst, whereas gold-catalyzed reactions exhibit inverted stereoselectivity, producing the corresponding E products.     

Cycloaddition reactions of 1,3-diazabuta-1,3-dienes with alkynyl ketenes

The cycloaddition reactions of ‘all-carbon’ 1,3-diazabuta-1,3-dienes with a few conjugated and unconjugated alkynyl ketenes are described. The reactions provide some interesting azetidinones and dihydropyrimidinones bearing an alkynyl moiety. The regiochemistry of cycloadduct is related with the degree of conjugation of the alkynyl ketene. Moreover, two alternative approaches to ‘all-carbon’ 1,3-diazabuta-1,3-dienes are reported.