Isocyanates benzoyl isothiocyanate

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. 

Formate esters behave as typical carbonyl compounds in reactions with a number of ylides, eliminating phosphine oxide and forming vinyl ethers, e.g. (33).35 Stabilized phosphoranes are able to condense with the carbonyl group of cyclic thioanhydrides (34).38 Quinoline derivatives, e.g. (35), are obtained from the condensation of dicar-boalkoxy-ylides with isocyanates.37 Benzoyl isothiocyanates and keto-phosphoranes give quantitative yields of (36), which are unreactive in Wittig reactions but can be readily oxidized by selenous acid.38 The products obtained from reactions (Scheme 9) with the triazolinedione (37) depend upon the stability of the ylide used.39... 

When acrylonitrile or ethyl acrylate was used as the dipolarophile, the azomethine adducts (134) and (135) were formed no thiocarbonyl ylide addition products were isolable in refluxing toluene or xylene, although the isoindoles (136a) and (136b) derived from them were isolated. In contrast to the reactions with fumaronitrile or AT-phenylmaleimide, the azomethine adducts (134) and (135) were still present at higher reaction temperatures — almost 50% in toluene and 4-5% in xylene. Under the same reaction conditions other electron-deficient dipolarophiles like dimethyl fumarate, norbornene, dimethyl maleate, phenyl isocyanate, phenyl isothiocyanate, benzoyl isothiocyanate, p-tosyl isocyanate and diphenylcyclopropenone failed to undergo cycloaddition to thienopyrrole (13), presumably due to steric interactions (77HC(30)317). 

The 3-carbazoyl group of pyrimido[l,2-a]azepine 462 was acylated at N-2 with benzoyl chloride, or reacted with aldehydes, isocyanates, or isothiocyanates (77MI1). 3-Bromohexahydropyrimido[l,2-fl]azepin-4-one was obtained from the 3-carboxylic acid 415 (R = = H, R = COOH) in the... 

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... 

Similar acylated isomunchnones were obtained with benzoyl isocyanate, phenyl isothiocyanate, and benzoyl isothiocyanate, as summarized for 516 517 (Fig. 4.155). " The authors " suggested that the NMR and IR spectra are more consistent with acylated isomunchnones than with bicyclic adducts 511. Thus the presence of an exchangeable proton at 9-11 ppm in the H-NMR spectrum and the amide carbonyl absorption in the IR spectrum at 1670 cm are not consistent with bicyclic lactam 511 but rather with isomunchnone amide 513. Likewise, the NMe absorption at 3.72 ppm in the H-NMR spectra of these adducts is at too low field to be expected for 511. When the authors follow the reaction in an NMR tube, they observe peaks for the 1 1 adduct 511 after 10 s, at 5.02 ppm (bridgehead methine) and 2.97 ppm (//-Me), which disappear after 30 min to give the NMR spectrum of 513. 

Reductions of ketones, sulfones, and sulfoxides with triphenyltin hydride have been shown to give hexaphenylditin as the tin-containing product 232, 237). Isocyanates or isothiocyanates 233, 239) as well as benzoyl peroxide 239a) also produce the same product from triphenyltin hydride. In contrast, however, alkyltin hydrides undergo addition to carbonyl groups to form alkyltin alkoxides 239b). 

While the cycloaddition reaction of phenyl isothiocyanates with nitrones proceeds across its C=N bond, substituted phenyl isothiocyanates, methyl isothiocyanate and benzoyl isothiocyanate react across their C=S bonds. However, these cycloadducts are not stable and they undergo fragmentation with formation of thioamides and isocyanates . ... 

The enol betaines derived from 1-phenacylpyridiniimi salts undergo analogous reactions. Characteristic examples are the formation of (32) and (33) from phenacylpyridinium enol betaine and phenyl isocyanate or isothiocyanate s and benzoyl chloride or benzoic anhydride, respectively. In a related casei54e reaction with carbon disulphide gives (34). 

Azoles containing a free NH group react comparatively readily with acyl halides. N-Acyl-pyrazoles, -imidazoles, etc. can be prepared by reaction sequences of either type (66) -> (67) or type (70)->(71) or (72). Such reactions have been carried out with benzoyl halides, sulfonyl halides, isocyanates, isothiocyanates and chloroformates. Reactions occur under Schotten-Baumann conditions or in inert solvents. When two isomeric products could result, only the thermodynamically stable one is usually obtained because the acylation reactions are reversible and the products interconvert readily. Thus benzotriazole forms 1-acyl derivatives (99) which preserve the Kekule resonance of the benzene ring and are therefore more stable than the isomeric 2-acyl derivatives. Acylation of pyrazoles also usually gives the more stable isomer as the sole product (66AHCi6)347). The imidazole-catalyzed hydrolysis of esters can be classified as an electrophilic attack on the multiply bonded imidazole nitrogen. 

A Wittig-type reaction of iminophosphorane 995 with benzoyl and ethoxycarbonyl isocyanates gave (91T6747) thiadiazolotriazines 996, whereas reaction of 995 with aromatic isocyanates afforded 997. On the other hand, iminophosphorane 995 reacted with methyl and benzyl isothiocyanates to give 998. Reaction of 995 with acid chlorides gave 999 (88H1935). All these compounds display mesoionic or zwitter ionic character (Scheme 184). 

N-3-Substituted 2-thioxo-4-quinazolinones 859 are formed when alkyl or aryl isothiocyanates are reacted with anthranilic acids or esters 857, <2001JME1710, 2002AP556, 2004JC0584, 2006JME2440>. The intermediate di-substituted thiourea 858 is normally not isolated, but is directly ring-closed in situ to the thioxoquinazolinone product 859. When 3-unsubstituted products are required, benzoyl isocyanate can be used <20008714>. 

Azoles containing a free NH group react comparatively readily with acyl halides. yV-Acyl-pyrazoles, -imidazoles, etc. can be prepared by reaction sequences of either type (75) — (76) or type (79)—>(80) or (81). Such reactions have been carried out with benzoyl halides, sulfonyl halides, isocyanates, isothiocyanates and chloroformates. Reactions occur under Schotten-Baumann conditions or in inert solvents. 

The reaction of ethyl 2-(l,2,3,4-tetrahydroisoquinolin-l-yl)acetate hydrochloride with potassium cyanate in boiling water gave 2,3,4,6,7,116-hexahydro-1 //-pyrimido[6,1 -a]isoquinoline-2,4-dione (69IJC684). 3,4,6,7-Tetrahydro-27/-pyrimido[6,l-fl]isoquinoline-2,4-dione and its 2-thioxo derivative were prepared in the reactions of l-methyl-3,4-dihydroisoquinoline with benzoyl isocyanate and ethoxycarbonyl isothiocyanate, respectively, in the presence of NEts (75CB1541). 

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