Thiobenzoyl isocyanate

A similar regiospecific [2 -I- 2] cycloaddition across a C=S group occurred when benzoyl isothiocyanate (436) and 2,3-diphenyl-1-azirine were heated in refiuxing benzene for 12 hours. The product obtained was shown to be (438) and an intermediate such as (437) could also be involved in this cycloaddition (74JOC3763). In contrast, thiobenzoyl isocyanate added in a [4-1-2] fashion, and after ring expansion gave a thiadiazepine derivative. 

The dimethylsulfonium ylide (568) added readily to aroyl isocyanates to give the intermediate addition product (569). This on heating underwent ring closure with loss of dimethyl sulfide to form the 4-hydroxyoxazole (570) (73T1983). This normal C-acylation of the sulfonium ylide also leads to thiazoles with thiobenzoyl isocyanate in this case the initial acylation product was not isolated, the thiazole being obtained directly. 

The azirine 1 reacts with thiobenzoyl isocyanate to give the Diels-Alder adduct 2. which at 80CC undergoes ring expansion to the thiadiazepinone 3, the only known representative of this ring system.327... 

The addition of thiobenzoyl isocyanate to norbornene and norbornadiene resulted in the thiazinones 230 (R = Ph) and 231, respectively (67CB685). The ter/-butyl- and mesityl-substituted analogs of 230 were prepared by the same method. In the case of a benzyl substituent, the derivative 232 containing an exo double bond was formed (81CB549). 

The urea (224) has been prepared from thiobenzoyl isocyanate and phenylhydroxylamine (Scheme... 

The 1,3,5-thiadiazepine (559) has been prepared by the thermal rearrangement of the [4 + 2] cycloadduct (558) of the azirine (557) and thiobenzoyl isocyanate (74JOC3763). The benzoyl isocyanate adduct does not rearrange to give an oxadiazepine. 

The reaction between thioacylformamidines and ketenes leads to thiazine-6-ones (29) (Scheme 16) (75T3055). 4-Amino-4//-thiazines (30) are obtained by condensation of thioacylformamidines with acetylenic compounds (Scheme 17) (85JOC1545). Thiobenzoyl-1 and )V,A/-diethylami-nothiocarbonyl isocyanates and isothiocyanates have been reacted with enaminoketones and ynamines. Enaminoketones and ynamines reacted with thiobenzoyl isocyanate give thiazine-4-ones 31 and 32, respectively (Scheme 18) (76BCJ2828 85ZC324). 

Thiobenzoyl isocyanate is widely used as a starting material for the syntheses of TAs 23-28 both in condensation with ethyl sodiocyanoacetate (86KGS3) and in [4 + 2]-cycloaddition reactions with alkenes and alkynes containing electron-donor groups (81CB2713 85ZC324) (Scheme 4). It is established that the rate of cycloaddition increases from alkenes to alkynes and with the electron-donor properties of substituents. 

The reaction of a thioamide or thiourea and an A/,(V-dimethylacylamide dimethyl acetal at room temperatures produces imino derivatives of type (327). The latter compounds readily condense with amino transfer reagents such as hydroxylamine-O-sulfonic acid and mesitylsulfonyloxyamine (MSH) to afford (301 R=H, Me R = aryl, ArNH, 4-pyridyl) in excellent yields. An unusual reaction of the E category is the condensation of nitrosobenzene with thiobenzoyl isocyanate, which produces the thiadiazolone (328) in 58% yield (Scheme 118) (73CB1496). Presumably, nitrobenzene is another reaction product, although this has not been characterized. 

Addition of thiobenzoyl isocyanate to the A-thiobenzoylketenimine (185) is accompanied by loss of COS and forms the violet 4-alkylidene-4/f-l,3,5-thiadiazine (186) possibly as outlined in Scheme 27 <85LA2305>. 

Finally, Nair and Kim have found that substituted 1-azirines will undergo [4 + 2] cycloaddition reactions with thiobenzoyl isocyanate, which acts as a heterodiene, yielding cycloadducts [Eq. (22)].77... 

The reaction of azirines (114) with benzoyl isothiocyanate has been discussed in terms of a (2 + 2)-cycloaddition of the azirine with the carbon-sulfur double bond, followed by rearrangement to the 2-benzamidothiazole (116).IU Experimental evidence for the formation of the (2 + 2)-cycloadduct (115) has not been provided. Reactions of azirines with other heterocumulenes such as thiobenzoyl isocyanate and... 

Thiobenzoyl isocyanate (313) may contribute four of the atoms (S—C—N—C) of the 1,2,4-thiadiazole ring system, the fifth being provided by a suitable nitrogenous compound. The reactant (313) is readily generated in situ from 2-phenylthiazoline-4,5-dione (312) in toluene.235 It reacts with ethereal hydrazoic acid with effervescence to yield 3-hydroxy-5-phenyl-... 

The interaction of thiobenzoyl isocyanates (318) and IV.lV -diphenyl sulfur diimide yields 2,5-diaryl-A4-l,2,4-thiadiazolin-3-ones (320) as very minor by-products (2%), presumably by way of the intermediate adducts (319).238... 

The 1,3,4-benzothiadiazepine (201 R = H, X = NCONH2), prepared by the reaction of o-thiocyanatoacetophenone with semicarbazide, decomposed at 200°C in diethylene glycol to give the benzisothiazole (202 R = H). Similarly, (201 R = NH2, X = O) gave (202 R = NH2) on heating with polyphosphoric acid. The l,3,5-thiadiazepine-4,6-diones (203) were formed in good yield as 2 1 adducts of trimethylsilyl cyanide and thiobenzoyl isocyanate. A new... 

Triphenyl-4,7-dihydro-l,3,5-thiadiazepin-4-one was prepared in 1974 by the reaction of thiobenzoyl isocyanate with 2,3-diphenyl-l-azirine <74JOC3763>. The second examples of this ring system, 1,3,5-thiadiazepin-6-ones (112), were prepared by the reaction of the isothiocyanate derivatives (110) with methanol or isopropylthiol. The initially formed adducts (111) were readily converted into the final products (112) upon treatment with a base, such as sodiiun methoxide (Scheme 18) <86S817>. 

Thiazinediones 513 are constmcted in 78% yield when ketenes react with thioacyl isocyanates, as in the reaction of thiobenzoyl isocyanate with diphenylketene (Scheme 168) (1972CB3322). These reactions are performed in ether or aromatic solvents in the absence of additives and catalysts. The isolation of azetidinedione as by-products has been reported. 

A series of recent papers documents solid advance within the chemistry of thioacyl isocyanates. Thus a variety of heterocyclic compounds have been obtained in (4+2) cycloaddition reactions of thiobenzoyl isocyanate (276) with aldehydes, diarylketens, ketenimines, benzylideneamines, ... 

Type F (C—N—C—S + C) Syntheses.—The condensation of thiobenzoyl isocyanate and diazoalkanes, with loss of nitrogen from the latter, affords... 

Thiazolo[2,3-b][l,375]tbiadiazines (C3NS-C3N2S).— Thiobenzoyl isocyanate reacts with A -thiazoline at —70 °C or with 2-methyl-A -thiazoline at room B. B. Molloy, D. H. Reid, and F. S. Skelton, J. Chem. Soc., 1965, 65. 

Type E Syntheses [CNCS + N].— The interaction of thiobenzoyl isocyanate and nitrosobenzene yields, surprisingly, the l,2,4-thiadiazolin-3-ones (79) (58%), with elimination of oxygen, the fate of which is as yet not elucidated. The formulation of the products is confirmed by their unequivocal synthesis by the oxidative cyclization of (80). ... 

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