Thiazetidine

Thiazetidines applications, 7, 484 electrophilic reactions, 7, 461 photochemical reactions, 7, 458-459 spectroscopy, 7, 455... 

Thermolysis of the thiadiazabicyclo[3.1.0]hexene 30, obtained from reaction of an azide with an isothiazole dioxide affords the 1,2-thiazetidine-1,1-dioxide 31, but in poor yield and as part of a three-component mixture <96T7183>. Isocyanates 32 are available in moderate yield <94ZOR1700>. 

Alkylidene sulfenes (75), generally prepared by the dehydrohalogenation of alkylsulfonyl chlorides, add readily to electron-rich multiple bonds. For example, with enamines, the thietane dioxide (e.g., 76) is formed diazoalkanes yield thiirane dioxides (episulfones) and imines (Schiff bases) afford 1,2-thiazetidine 1,1-dioxides. There are available numerous reviews of sulfenes, including cycloaddition reactions.102... 

Raasch, and Schaumann and co-workers, have studied the reactions of bis (trifluoromethyl)thioketene (83 R1 = CF3) with alkenes, with thioketones, and with carbodiimides or Schiff-base imines. The products were, respectively, thietans, 1,3-dithietans (84 R1 = CF3), and 1,3-thiazetidines (85 R1 = CF3) (from the carbodiimide).114,115 With phenyl azide the 1,2,3,4-thiatriazoline (86 R = CF3) is formed subsequent pyrolysis yields2,l-benzisothiazole.114... 

A stereoselective one-pot synthesis of substituted 1,2-thiazetidine 1,1-dioxides (P-sultams) 55 started from heterocyclic pentafluorophenyl (PFP) sulfonates <06OL5513>. 

Thermolysis of the pentacoordinate 1,2-thiazetidine 1-oxide 56, which was synthesized for the first time and characterized by X-ray crystallographic analysis, gave the corresponding aziridine 57 and a cyclic sulfinate almost quantitatively <06OL4625>. 

Thiazetidine 1,1,-dioxides ((3-sultams) 67 were directly synthesised from pentafluorophenyl (PFP) isoxazolidine-4-sulfonates 66 under mild reducing conditions [Mo(CO)6, MeCN, H20, reflux]. The process is stereoselective and goes through N-O bond cleavage followed by intramolecular displacement of the PFP group by the amine <06OL5513>. 

Regioselective hydrolysis of the diester 27 gave the 1,3-thiazetidine 28 where the thiazetidine ring is fused to a quinolone nucleus <99CPB1765>. Derivatives of the tricyclic system, e.g. 29, showed activity against gram-positive bacteria including quinolone-resistant MRS A <99H(51)2915>. 

In a study on [l,2,4]triazolo[3,4-3][l,3,5]thiadiazines, mass spectral fragmentation of the 3-aryl-6-methyl derivative 33 (see Scheme 2) has been determined by Wang et al. <2001SC2841>. These authors found that elimination of the methylimine formaldehyde takes place first to form a thiazetidine ring 34 and, finally, removal of a CH2 group the 2-mercapto-5-aryl[l,2,4]triazole 35 can be observed. 

Cyclization of diethyl [3-(4-acetyl-l-piperazinyl)-4-fluorophenyl-l,3-thiazetidin-2-ylidene]malonate (1291) in polyphosphoric acid at 120°C for 1 hr gave a mixture of l,3-thiazeto[3,2-a]quinoline-3-carboxylate (1292, R = Et 25%) and 3-carboxylie acid (1292, R = H 20%) (87BRP2190376). Ring closure was also carried out in fuming sulfuric acid at 100°C for 5 min to afford l,3-thiazeto[3,2-fl]quinoline-3-carboxylic acid (1292, R = H) in 98% yield. 

The sodium salt of mercapto[phenylamino]methylenemalonate (342, R = 4-acetyl-1-piperidinyl, X = Na) in THF was added drop wise to a solution of methylene iodide in DMF in the presence of potassium carbonate at 60°C for 2 hr to give diethyl (l,3-thiazetidin-2-ylidene)malonate (1291) in 50% yield (87BRP2190376). 

Unstable 2,3-dialkyl-l,2-thiazetidine 1,1-dioxides 315 (R1 = Bu or C6H13 R2 = Et, i-Pr, t-Bu or PI1CH2) are produced from the ethenesulphonyl fluorides 314 and primary... 

There are two reports describing the preparation of derivatives of 1,2-thiazetidine-1,1-dioxide. The sulfur atom in L-cystine diethyl ester was oxidized and the corresponding sulfonyl chloride was cyclized with ammonia (Scheme 3) (60CB784). A similar transformation used protected )3-homocysteine as starting material (94LA251). 

The formal insertion of RNCS (R = Ph, 4-Me-C6H4) into the Re—OR bonds of [ReO-Cl2(OR )(PPh3)2] complexes and the formation of the complexes [ReOCl2(PPh3) R N=C-(OR )S ] (173) has been observed. The thiazetidine ligand is formally monoanionic and is coordinated with an almost planar four-membered ring. ... 

Fused 5-imino-l,2,4-dithiazolidine-3-thiones and 3-imines (100) take up nucleophiles on one sulfur atom, releasing the XCS structural unit of the heterocycle (Scheme 15) <85JCS(P1)1007>. Nonfused analogues (101) give up one sulfur atom to the nucleophile, the rest of heterocycle closing to form a 1,3-thiazetidine ring (102) (Scheme 16) <87ZC142>. 

The present review is concerned with four-membered heterocycles that contain one sulfur atom either alone or associated with another heteroatom. The classes of compounds that will be discussed are the thietanes (1) and thietes (2), the 1,2-oxathietanes (3), the / -sultines and -sultones (4 and 5), the 1,2- and 1,3-thiazetidines (6 and 7) and thiazetes (8), the 1,2- and 1,3-thia-phosphetanes (9 and 10), and the 1,3-silathietanes and 1,3-selenathietanes (11 and 12). 

Thiazetidines are investigated with special emphasis on their possible antiradiation drug activity. Certain 1,3-thiazetidines exhibit pesticidal activity. Compounds 21 are specifically eflective as insecticidal and acaricidal agents. 

Exact molecular parameters of oxathietanes and thiazetidines have not been assessed, although the nonplanar puckered-ring structure appears to be the most favorable orientation. ... 

The UV spectra of 1,2-thiazetidinone oxides have been recorded by Beeken and Korte. Measured in cyclohexane or chloroform, the N-substituted cyclohexyl- (35), phenyl-, and aryl-substituted 4,4-bisphenyl-l,2-thiazetidin-3-one 1,1-oxides showed an average absorption band at = 240 nm... 

The complete IR spectrum of thiete has been reported by Dittmer et The most characteristic bands of thiete are the C—H stretching vibration at 3165 cm" and the C=C stretching mode at 1543 cm" Thiete derivatives often show the latter absorption band at 1620 cm " A collection of IR data on the thiazetidines has been assembled. ... 

Extensive investigations into the IR absorption properties of the thiazetidines have been carried out. " The IR spectra of jS-sultones have been analyzed by Truce and Kao Liu. ... 

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