Trithiazyl trichloride, reactions

Treatment of ethenes 158 with trithiazyl trichloride afforded 1,2,5-thiadiazoles 159 in moderate to good yields (Equation 32 Table 10). The reaction, however, suffers from the possibility of chlorination at allylic or benzylic positions, in particular if excess trimer is used. 

Table 10 Reaction of alkenes 158 with trithiazyl trichloride to give 1,2,5-thiadiazoles 159...

Similarly, conjugated dienes, enynes, and diynes such as ( , )-l,4-diphenylbuta-l,3-diene 162, fE)-l,4-diphenyl-but-l-en-3-yne 163, or l,4-diphenylbuta-l,3-diyne 164 on treatment with trithiazyl trichloride (2 equiv) afforded the bisthiadiazole 165 in moderate to good yield (40-60%), depending on the reaction conditions (Scheme 24) <1997CC1493, 1997J(P 1)3189, 1998CC1207>. 

A-Alkylpyrroles undergo cycloaddition reactions with trithiazyl trichloride (NSC1)3 to afford, depending on the substituents R1, R2, and R3, thiadiazoles 216-218. The reactions are proposed to proceed by addition of the N-S(C1)-N fragment across the 2,3- and the 4,5-bonds of the A-alkylpyrrole, followed by a series of eliminations to give the observed products (Equation 49) <1997CC1493, 1997J(P 1)3189>. 

The reaction of 1,4-diphenylbuta-l,3-diene (2) with trithiazyl trichloride (3) yields a bi(thiadiazole) (4), an isothiazoloisothiazole (5), a dithiazolothiazine (6), and two thiazin-odithiatriazepines (7) and (8) by 1,2-, 1,3-, and 1,4-cycloaddition reactions (Scheme 2). The bridged-mode (/3-tether) tandem inter-[4 -E 2]/intra-[3 -E 2] cycloaddition of (ii)-2-methyl-2-nitrostyrene (9) with 1-butoxypenta-1,4-diene (10) produces stable tricyclic nitroso acetals (11) which afford, after reduction and protection, highly functionalized aminocyclopentanedimethanol triacetates (12) (Scheme 3). ... 

When N-substituted pyrrole 37 and trithiazyl trichloride (NSCfis are heated at reflux in carbon tetrachloride, IH-pyrrolo[2,3-r 4,5-. V-Substituted pyrrolo[2,3-f]-l,2,5-thiadi-azole 38 is believed to be an intermediate in this reaction (Equation 2). The enamine character of the carbon-carbon double bond of 38 is presumed to be enhanced compared to pyrrole 37, rendering 38 more reactive toward (NSCfis. 

Rees and co-workers in their study of the reactions of trithiazyl trichloride in the preparations of heterocyclic compounds have noted that the isothiazolo[5,4-, isothiazole compound 140 was produced in low yield on reaction with conjugated dienes, along with the other heterocyclic systems 142-145 in much higher yields (Equation 28). Since it is known that trithiazyl trichloride is in thermal equilibrium with its monomer NSCl (Equation 29), the authors propose the so-called criss-cross cycloaddition reaction (Equation 30) which has been reported for azabu-tadienes, but this represents the first example of such a criss-cross cycloaddition to an all-carbon diene <1998CC1207>. 

Nucleophilic attack at nitrogen is rare in these systems. However, the inorganic trithiazyl trichloride (87) acts as an apparent source of electrophilic nitrogen on reaction with certain organic substrates. Reaction with electron-rich alkenes such as stilbene gives 3,4-diphenyl-1,2,5-thiadiazole (77JCS(Pl)916>. 

Evidence has been presented for initial electrophilic substitution by thiazyl chloride (NSC1) in die reaction of trithiazyl trichloride with 2,5-diarylfurans (38) which eventually yields 5-aroyl-3-arylisothiazoles.86... 

Thiadiazoles have been prepared111 in a one-pot reaction of trithiazyl trichloride with alkynes (see Scheme 25). 

I )ithijzolc[4.5-r/]thiazinc. Y-oxidc 150 is formed in low yield by the reaction of trithiazyl trichloride ((NSC1)3>, which is in thermal equilibration with its monomer (N=S-C1), with l,4-diphenyl-l,3-buta-l,3-diene followed by oxidation with air (Scheme 28) <1998CC1207>. The structure of product 150 was confirmed by X-ray crystallography. The mechanism of this transformation involves an initial 1,4-cycloaddition process. 

The synthesis of 1,3,2-dithiazolidines from bis(sulfenylchlorides) and amines has been developed in the 1990s and 2000s (Equations 12 and 14). Trimethylsilyl azide confirmed its important role in the preparation of fused mono- and bis-l,3,2-dithiazolium cations (Equation 18). Oakley and co-workers showed that o-dimercapto derivatives can be used in the synthesis of these compounds if treated with trithiazyl trichloride (Equation 19). Synthesis of iV-substituted 1,3,2-benzodithazole tetraoxide has been successfully carried out from benzene-bis(sulfonylchloride) and aliphatic amines (Equation 15). An important feature in this reaction is the preparation of chiral derivatives from optically pure amines (Equations 16 and 17). 

Thiadiazoles can be prepared by the oxidative cyclisation of 1,2-diamines or aminocarboxamides. Condensation of snlfamide (S02(NH2)2) with 1,2-diketones gives 1,2,5-thiadiazole 1,1-dioxides. A good general method is the reaction of trithiazyl trichloride with activated alkenes and alkynes this method is also useful for the fusion of a 1,2,5-thiadiazole onto other heterocycles, such as pyrroles. The reaction possibly proceeds via cycloaddition to an N-S-N unit in the trithiazine ring. "... 

Trichloro(thionitrosyl)bis(triphenylphosphine)ruthenium(II)was previously prepared by the reaction of trithiazyl trichloride in THF with RuCL xHjO and triphenylphosphine in absolute ethanol. The product crystallizes over a period of several hours, and the yield is very poor. The same complex can be prepared from dichlorotris(triphenylphosphine)ruthenium(II) in CH2CI2 and trithiazyl trichloride in tetrahydrofuran (THF) in a better yield and in less time. 

Rees has begun a series of investigations into the reaction of variously substituted pyrroles and indoles with trithiazyl trichloride (34) as a route to bisheterocycles <97CC1493>. In the simplest manifestation of this process, reaction of 34 with 2,3-unsubstituted pyrrole 35 in hot CCI4 gives the 2,3-fused 1,2,5-thiadiazolo derivative 36 <97JCS(P1)2695>. 

The optimum yield of the chloropropyl 1,2,5-thiadiazole 97 was produced by treatment of the enamino-ester 95 with trithiazyl trichloride (92) in boiling CCI4. It was postulated that the reaction proceeded via the thiadiazolium salt 96 which could be then dealkylated by chloride ion to give 97 <01JCS(P1)662>. 

Reaction of trithiazyl trichloride (92) with cnamidcs 98 provided a new route to aryl-l,2 -thiadiazoles 100. The reaction presumably proceed via the N-acylthiadiazolium salts 99 which were too sensitive to be isolated <01JCS(P1)662>. 

Finally, condensation of trithiazyl trichloride (92) with 1,2,3-triazoles 101 with electron-withdrawing substituents gave 1,2,5-thiadiazolcs 102. Although the scope of this reaction is limited, it does provide an attractive route to thiadiazoles with electron-withdrawing substituents <01JCS(P1)662>. 

Reaction of [CpCr(CO)3] Na+ with S3N3CI3 (/.e., trithiazyl trichloride) affords both [CpGr(CO)a(NS)] and [ CpCr(CO)a 2S], whose crystal structures have been determined. Rates of displacement of halide from alkyl halides by [CpMo(CO)3]" are sensitive to steric, leaving-group, and counter-ion effects. Attachment of the Gp ligand in [CpMo(CO)3]H to polystyrene has little effect upon the Bronsted acidity of the complex. The chemistry of bis-alkyne complexes of Mo and W of the types [CpM( -hfb)aCl] and [CpM(CO)( -but-2-yne)2]+[PF6] has been further explored. Reactions of the carbyne complex [CpW(CO)a(CAr)] (Ar=p-tolyl) with chelating bisphosphines afford [Pg.288]

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