Tetrahydro-1,2,4-thiadiazine 1,1-dioxide

There are only a few reported members of this series. The first mentioned is 3,4,5,6-tetrahydro-3-phenyl-2//-l,2,3-thiadiazine 1,1-dioxide, which is prepared in low yield by cyclization of N-3-chloropropylsulfonyl-N -phenylhydrazine with base (62JPR56). The well-known property of azoalkenes to undergo [4 + 2] cycloaddition reactions with dienophiles can be exploited to give 1,2,3-thiadiazines. Thus, N-phenylazostilbene, PhCH=C(Ph)N=NPh, reacts slowly with sulfine 1 at room temperature to yield the trans (44%) and cis (13%) isomers 2 and 3... 

The main successful applications of monocyclic 1,2,4-thiadiazines in earlier years have been the use of bis[4-(3,4,5,6-tetrahydro-l,l-dioxo-2//-l,2,4-thiadiazinyl)]methane (62, Taurolidine, Taurolin, Drainsept) as an antibacterial agent and 3,4,5,6-tetrahydro-2//-l,2,4-thiadiazine 1,1-dioxide (63, Taurultam) as both an antibacterial and antifungal agent (66FRP1458701). Claimed uses of 1,2,4-thiadiazines are listed in Table 11. 

Most 1,2,3-thiadiazines are tetrahydro derivatives that exist as the 1,1-dioxides.12 17 However, the novel, heterocyclic 8n -electron systems 4 and the corresponding 1,2,3-thiadiazines have been prepared.18 Reaction of the 2-chlorocycloalkene-l-carbaldehydes l12 with potassium thiocyanate in aqueous ethanol affords the 2-thiocyanatocycloalkene-l-carbaldehydes 2 which react in the usual fashion with hydrazines to furnish the hydrazones 3a, b. When the hydra-zones 3 a, b are dissolved in 70 % perchloric acid under ice-cooling, hydrogen cyanide is evolved and the 1,2,3-thiadiazinium perchlorates 4a, b crystallize within a short time. Addition of an excess of triethylamine to 4a liberates the 1,2,3-thiadiazine while treatment of 4b with methanolic potassium hydroxide solution furnishes 5 b. 

The tetrahydro-27/-thiadiazine 1,1-dioxides (168) are accessible by reduction and regioselective deoxygenation of 4,5-dihydro-6/7-l,2,6-thiadiazine 1,1,2-trioxides (167) (Section 6.16.9.2.3.1) with sodium borohydride (Equation (18)) <90LA775>. 

Oxidation of 3,5-dialkyl tetrahydro-4//-l,3,5-thiadiazin-4-ones with one equivalent of MCPBA in chloroform at room temperature yields the 1-oxides (91) in 31-60% yield. With an excess of oxidant, the 1,1-dioxides (92) are produced <72JHC23l>. 

The scope of the reaction was probed by extending the reaction to the synthesis of six-membered cyclic sulphamides. The reaction of 367 with acetamidine gave 1,2,4,6-thiatriazinone-1,1-dioxides 371 (equation 121) in yields of 20%. Fragmentation of the intermediates prior to cyclization is considered to account for the low yields. Modest yields of the pyridothiatriazinone 372 were obtained by condensation of aminopyridine with 367 (equation 122). Aminotriazoles when reacted with 367 yielded the triazolothiatriazinones 373 (equation 123). The reaction of 2-amino-3-ethoxycarbonyl 4,5,6,7-tetrahydro-l-benzothiophen (374) with isopropyl sulphamoyl chloride gives the iV-(isopropyl)-iV -(3-ethoxycarbonyl-4,5,6,7-tetrahydro-l-benzothiophene)sulphamide (375)369. Cyclization of 375 with 5% sodium hydroxide leads to the formation of the cyclic sulphamide 3-isopropyl-4-oxo-3,4,5,6,7,8-hexahydro-1H [ 1 ] -benzothieno [2,3-d] -2,1,3-thiadiazin-2,2-dioxide (376) in 42% yield. Decarboxylation of 375 also occurs in the reaction with the formation of iV-(isopropyl)-iV -(4,5,6,7-tetrahydro-l-benzothiophene)sulphamide 377... 

Chem. Descrip. Tetrahydro-3,5-dimethyl-2H-1,3,5-thiadiazine-2-thione CAS 533-74-4 EINECS/ELINCS 208-576-7 Uses Rreservative for pigment slurries ind. those based on aluminum silicate, calcium carbonate, and titanium dioxide for use in coated/un-coated paper/papetboard for food contact applies. food-contact slimickte bactericide in leather prod. 

Thiacyclopentadiene. See Thiophene Thiacyclopentane. See Tetrahydrothiophene Thiacyclopentane dioxide. See Sulfolane 2H-1,3,5-Thiadiazine-2-thione, tetrahydro-3,5-dimethyl-. See 3,5-Dimethyl tetrahydro-2-H,1,3,5-thiadiazone-2-thione... 

METASOL D3T is a preservative effective against a broad spectrum of bacteria and fungi in coatings, clay slurries, adhesives, glues, latex, emulsions, casein, and titanium dioxide slurries. Chemically, the product is tetrahydro-3,5-dimethyl-2H-l,3,5-thiadiazine-2-thione. 

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