Iminodithiocarbonic

Other miscellaneous imines that underwent photoreaction with chromium alkoxycarbenes include iminodithiocarbonates [33],the mono-N-phenylimine of benzil and the bis-JV-phenyl imine of acetoin [20]. By preparing the chromium carbene complex from 13CO-labeled chromium hexacarbonyl, /J-lactams with two adjacent 13C labels were synthesized [34]. 

Pyrazolo[l,5-a][l,3,5]triazines 58 were obtained by an efficient one-step reaction from iminodithiocarbonates 54 and pyrazole 55, or by an alternative two-step reaction form the aroyl isothiocyanates 56 and pyrazole 55 <06TL5441>. 

Care must be taken in the choice of organic solvent. Chloroform should never be used under the basic conditions due to the risk of the formation of isocyanides (see Chapter 7) and the use of carbon disulphide can lead to formation of dithiocarba-mates, e.g. dimethyl A -(ethoxycarbonylmethyl)iminodithiocarbonate is formed (35-39%), as the major product in high purity, in the liquiddiquid two-phase methyl-ation of ethyl glycinate in carbon disulphide [15]. The product is useful as an intermediate in the synthesis of thiazoles [15] and dihydrooxazoles [16]. 

Similarly, the iminodithiocarbonate 72 serves as a thio nitrile ylide synthon (38). When treated with fluoride ion in the presence of aldehydes and ketones, it gave the alcohols 73 as isolable products that were converted into 74 on treatment with silical gel. Best results were obtained with aromatic aldehydes containing electron-withdrawing groups yields were poorer when electron-donating groups were present and for ketones. 

Poly(iminothiocarbonates) and poly(iminodithiocarbonates), both of which are terminated with an isocyanate group, are obtained from l-(aryloxythio-carbonyl)aziridines and 1 -(aryldithiocarbonyl)aziridines, respectively. 

Solid-phase syntheses of triazines (Table 15.32) include the cyclocondensation of polystyrene-bound isothiuronium salts with /V-(cyano)iminodithiocarbonates and the cyclization with simultaneous cleavage from the support of derivatives of a-amino acid hydrazides (Table 15.32). (Benzylthio)triazines, such as those listed in Table 15.32 (Entries 1 and 2), have been cleaved from a support by oxidation to sulfoxides or sul-fones with N-benzenesulfonyl-3-phenyloxaziridine, followed by nucleophilic cleavage with primary or secondary aliphatic amines or with electron-rich anilines (see Section 3.8). 

N-Bis(methylthio)methylene derivatives of amines (iminodithiocarbonates) were first introduced by Hoppe and Beckmann468 for the synthesis of a-amino acids from glycine. The A bis(methylthio)methyleneamines are prepared by reaction of a primary amine with carbon disulfide (HAZARD) in the presence of triethylamine and iodomethane to form a methyl dithiocarbamate derivative, which is then S-alkylated with a second equivalent of iodomethane in the presence of potassium carbonate as the base. Scheme 8,233 illustrates an alternative one pot procedure applied to the synthesis of /erf-butyl N-[bis(methylthio)-methylene]glycinate and its use in diastereoselective conjugate addition under... 

Synthesis of 1,3-selcnazole derivatives has been achieved by reactions of dimethyl A -(ethoxycarbonylmethyl)iminodithio-carbonate with selenothioethanoic acid 3 -ester < 1997JA8592>. Nucleophilic attack of the carbanion derived from dimethyl A -(ethoxycarbonylmethyl)iminodithiocarbonate at the C=Se group, followed by the elimination of -butyl thiolate, affords an intermediate which forms the selenazole by intermolecular nucleophilic attack (Scheme 11) <2003NJC1622>. 

Olefin synthesis. This reagent has an advantage over trialkyl phosphites (see Trimethyl phosphite, 1, 1233, and this volume) for stereospecific generation of olefins from trithio- and thionocarbonates in that the conditions are mild (30°)-s Thus optically active /rans-cyclooctene (6) has been prepared from cis-cyclooctene in the following way.3 Addition of thiocyanogen to cis-cyclooctene (3) affords trans-, 2-dithiocyanocyclooctane (4), which when refluxed with 47% hydrobromic acid affords the iminodithiocarbonate (5). This was resolved via the salt with (—)-l-phenyl-ethanesulfonic acid by thirteen recrystallizations from 2-butanone. The (+)-(5) was... 

Similar to )V-acyl- and (V-cyanoimidates, A-acyl- and jV-cyanoimidodithiocarbonates 20 react with amidines to form sulfanyl-substituted 1,3,5-triazines 21.425 427a,b The amidine hydrochloride is treated with an equimolar amount of base to liberate the amidine, which is reacted in alcoholic solution with the activated iminodithiocarbonate. When evolution of methanethiol has subsided, the reaction products are crystallized by cooling the reaction mixture.4,25... 

Because of their predictable behavior and reactivity, thioacyl isocyanates comprise the bulk of this work, and extensive studies of their [4 + 2] reactions with olefins,83 enamines,84 enol ethers,843 thioacyl isocyanates,85 imines,85 1 86 carbodiimides,84387 isocyanates,843 azirines,88 /3-enaminoke-tones,89 dianils,86d azines,90 hydrazones,91 imidazoline-4,5-diones,92 aryl cyanates,93 disubstituted cyanamides,93 aldehydes,94 ketones,94 ketenes,94 alkyl or aryl iminodithiocarbonates,95 and the carbon-carbon double bond of ketenimines96 have been detailed. In an extensive comparative study of the [4 + 2] cycloaddition reactions of thioacyl isocyanates, the heterocu-mulenes bearing strong electron-withdrawing substituents were found to be more stable and less prone to participate in cycloaddition reactions.84 Representative examples are summarized in Scheme 9-IV. 

Amide mercaptals Dithiocarbamic acid esters Dithiourethans Iminodisulfides Iminodithiocarbonic acid esters... 

A soln. of dimethyl N-(ethoxycarbonylmethyl)iminodithiocarbonate in THF added drop wise to a stirred soln. of K-/cr/-butoxide in the same solvent at -78° under N2, a soln. of phenyl isothiocyanate in the same solvent added slowly after 30 min, stirring continued at —78° for an additional 30 min, the mixture allowed to stand at room temp, for 2 h, then quenched with water 4-ethoxycarbonyl-2-methylthio-5-anilino-thiazole. Y 90%. F.e.s. C. Alvarez-Ibarra et al.. Heterocycles 27, 2177-83 (1988). 

Iminodithiocarbonic acid esters Dithiocarbimidates 15 Immoniodithiocarbonate esters Mercaptal S-arylimines Sulfenylthiocyanates... 

Iminodithiocarbonic acid esters. Phenyl isocyanide dichloride heated 7 hrs. at 110° with dimethylthallium thiophenoxide in toluene diphenyl N-phenyldithio-carbonimidate. Y 88.6%. F. e., also replacement of one Cl-atom and stepwise replacement by 2 different functions, s. B. Walther and W. Kolbe, Z. Chem. 13, 192 (1973). 

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