Studies on 4-Thiazolidinones: Scope of the Reactions of 3-Aryl-2-thioxo-1,3-thiazolidin-4-ones with Cyanide and Cyanate Ions (original) (raw)
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Synthetic, Mechanistic, and Structural Studies Related to 1,2,4-Dithiazolidine-3,5-dione
The Journal of Organic Chemistry, 1996
Reaction of O-ethyl thiocarbamate (4) with (chlorocarbonyl)sulfenyl chloride (5) gives 3-ethoxy-1,2,4-dithiazolin-5-one (2) and 3,5-diethoxy-1,2,4-thiadiazole (3), with the relative amounts of 2 and 3 formed depending very much on the solvent (e.g., diethyl ether favors 2; chloroform favors 3). The effects of added base, order of addition, concentration, and temperature were also studied. Mechanisms for the observed transformations have been proposed and are supported by the characterization of relatively unstable acyclic intermediates, e.g., formimidoyl(chlorocarbonyl)disulfane 8, symmetrical bis(formimidoyl)disulfane 10, and ethoxythiocarbonyl imidate 11, which are obtained under alternative conditions. Compound 2 is converted with concentrated aqueous hydrochloric acid upon short reflux to 1,2,4-dithiazolidine-3,5-dione (1), rearranges upon prolonged melting to give principally N-ethyl-1,2,4-dithiazolidine-3,5-dione (13), and is desulfurized with various trivalent phosphorus compounds to yield O-ethyl cyanate (15) plus carbonyl sulfide. X-ray crystallographic structures of 1 and 2 have been solved; the planarity and aromatic character of these molecules help to explain some of their reactions. Recent work from our laboratory 2 has shown that 1,2,4dithiazolidine-3,5-dione (1), a compound first prepared by German scientists several decades ago, 3-5 is a highly effective sulfurization reagent that provides access to phosphorothioate analogues of DNA and phosphopeptides. In addition, 1 represents a protected form 6 of ammonia and may be useful for mild homologation of the classical Gabriel synthesis. 7 The present contribution reports an efficient, optimized two-step procedure for the preparation of 1, via the key intermediate 3-ethoxy-1,2,4dithiazolin-5-one (2), 8 and also describes how the reaction designed to give 2 provides entry to another heterocycle, 3,5-diethoxy-1,2,4-thiadiazole (3). 9 In addition, X-ray crystallographic analyses of 1 and 2 confirm the planar aromatic character of each heterocycle and facilitate the understanding of some reactions of the title heterocycles 1 and 2. Results and Discussion Reaction of O-Ethyl Thiocarbamate (4) with (Chlorocarbonyl)sulfenyl Chloride (5). With the goal to prepare alkyl-free heterocyclic disulfide 1, reaction of 4 10 with 5 11 was found to stop at heterocycle 2 (Scheme 1). 3a,c A second isolable product from the reaction was 3,5-diethoxy-1,2,4-thiadiazole (3, Scheme 1), 9 and the
Syntheses, spectroscopic characterization and crystal structures
Polyhedron, 2006
Some new phosphoramidates with formula 4-F-C 6 H 4 C(O)N(H)P(O)X 2 , X = NC 4 H 8 (1), NC 5 H 10 (2), 4-CH 3-NC 5 H 9 (3), NC 4 H 8 O (4), NC 6 H 12 (5), N(CH 2 CH 3) 2 (6), N(CH 2 CH 2 CH 3) 2 (7) were synthesized. The reaction of compound 2 with dimethyltin(IV) dichloride leads to an octahedral organotin(IV) complex, SnCl 2 (CH 3) 2 [4-F-C 6 H 4 C(O)N(H)P(O)(NC 5 H 10) 2 ] 2 (8) with equal ligands in trans positions. These compounds were characterized by IR, 1 H, 13 C, 31 P, 119 Sn NMR, mass spectroscopy and elemental analysis. The structures have been determined for compounds 1, 2, 4, 5 and 8. Compound 2 exists as four symmetrically independent molecules in the crystalline lattice. Compounds 1, 4 and 5 form dimmers via intermolecular-P@OÁ Á ÁH-Nhydrogen bonds that in 1 is centrosymmetric. In compound 2, two dimmers were formed; each of them was produced between two adjacent independent molecules. In compounds 1, 2, 3, 4 and 8, containing five-and six-membered ring amine groups, 3 J(P,C aliphatic) > 2 J(P,C aliphatic). Compound 5 with seven-membered ring amine, similar to compounds 6 and 7 with acyclic aliphatic amines, shows that 2 J(P,C aliphatic) > 3 J(P,C aliphatic). Mass spectra of these compounds indicate the 4-F-C 6 H 4 CO + and 4-F-C 6 H 4 CN + fragments.
11.Use of 0002www.iiste.org Call_for_Paper-Ethoxy(4H)-3,1-benzoxazin-4-one as a Precursor
The interactions of 2-ethoxy(4H)-3,1-benzoxazin-4-one (1) with various nitrogen nucleophiles such as ammonium acetate, hydrazine hydrate, ethanolamine, p-phenylenediamine, o-phenylenediamine, otolidine, dapsone, 2-aminophenol, 4-aminophenol, 4-aminobenzoic acid and 2-aminonicotinic acid have been discussed. The reactions of 2-thoxy-(3H)-quinazolin-4-one with ethyl chloroformate, phosphorus pentasulfide, chloroacetyl chloride and phosphorus oxychloride have also been investigated. Similar reactions of 2-ethoxy-4-chloroquinazoline with hydrazine hydrate and thiosemicarbazide have been introduced. Aminolysis of the 2-ethoxy group in some of the thiadiazoloquinazolinone derivatives has been attempted. The interactions of these aminolized derivatives and the 3-aminoquinazolinone with chloroacetyl chloride have been studied. All of the synthesized derivatives have been used in a wide range as starting materials for the synthesis of novel quinazoline and/or quinazolinones which have biological activity. The structures of all these products, obtained by heterocyclic ring opening and ring closure, were inferred by the IR, MS, 1 H NMR spectral as well as elemental analyses.
Liebigs Annalen der Chemie, 1986
Synthese von Heterocyclen, L ').-Synthese von 2,4-Diaryl-5-cyan-l,6-dihydrod-thioxo-3-pyridincarbonsaure-ethylestern aus u-Benzoylzimtsaure-ethylestern Die Umsetzung von a-Benzoylzimtsaure-ethylestern 2 mit Cyanthioacetamid (1) in Methanol/Natriummethanolat fiihrt zu den Natriumsalzen der 2,4-Diaryl-5-cyan-l,2,3,4-tetrahydro-2-hydroxy-6-mercapto-3-pyridincarbonsaure-ethylester 3. Diese konnen zu Methylthio-Derivaten 4 methyliert oder zu Dihydropyridonen 5 dehydratisiert werden. Die Verbindungen 4 werden mittels Nitrosylschwefelsaure zu den entsprechenden aromatischen 2-(Me-thy1thio)pyridinen oxidiert. Andererseits fuhrt eine ahnliche Behandlung der Derivate 5 zwar zu Aromatisierung, aber isoliert werden die Disulfide 6. Reduktion dieser Disulfide ergibt 2-Thiopyridone 7, woraus die zugehorigen 2-Pyridone 9 hergestellt werden konnen. Diese Produkte entstehen auch bei der basischen Hydrolyse von (Methy1thio)pyridinen 8. In a previous paper in this journal*', we reported on the synthesis of 2-pyridinethiones involving the reaction of cyanothioacetamide (1) with u-benzoylcinnamonitriles from which 4,6-diaryl-1,2-dihydro-2-thioxo-3,S-pyridinedicarbonitriles were obtained. As an extension of this synthesis, we now report on the reaction of 1 with ethyl ct-benzoylcinnamates. This reaction leads to several hitherto unknown 2-pyridinethiones and related compounds. On treatment of ethyl a-benzoylcinnamates 2 with cyanothioacetamide (1) in ethanol solution and in the presence of sodium methoxide as the basic catalyst, conjugate addition at the double bond of the cinnamates 2 takes place, followed by spontaneous cyclization to give a nitrogen-containing ring. However, neither dehydration nor aromatization takes place and the stable sodium salts 3 are obtained. These species seem to be stabilized by an intramolecular hydrogen bond in the configuration shown, responsible for the remarkable high-field shifts of the 'H signals due to the methyl (6 = 0.4) and methylene group (6 = 3.5) (Table 2) of the equatorial ethoxycarbonyl function, shielded by the two contiguous aryl groups. The 'H NMR spectra of these compounds show also a pair of doublets at about 6 = 4.1 and 2.7 with a coupling constant of 12 Hz, indicating a trans-diaxial configuration of 4-H and 5-H. The hydroxy signal appears as a broad singlet at rather low field (6 N 5.8). The OH and NH groups give rise to a broad band at 2800-3600 cm-' in the IR spectra,