Hydroxy thiocyanate

Bellomo A, Gonzalez D (2007) Diasterodivergent Synthesis of Optically Pure Vinyl Episulfides and P-Hydroxy Thiocyanates from a Bacterial Metabolite. Tetrahedron Lett 48 3047... 

One of the most important syntheses of thiirans is the direct conversion of oxirans to thiirans with thiocyanate salts . The mechanism proposed is opening of the oxirane (62) to hydroxy thiocyanate (63), rearrangement to mercapto cyanate (65) through the cyclic intermediate 64 and finally elimination of cyanate ion to give the thiiran 66. 

Bellomo A, Gonzalez D. Diasterodivergent synthesis of optically pure vinyl episulHdes and [beta]-hydroxy thiocyanates from a bacterial metabolite. Tetrahedron Lett. 2007 48 3047-3051. 

Hydroxy-4-methylthiazole has been prepared in 68% yield through the reaction of barium thiocyanate with chloroacetone (70). 

Acetic anhydride has also been used as the acylating agent. The formation of thiiranes from thiocyanatohydrins having a tertiary hydroxy group is best achieved by p-toluenesulfonic acid-catalyzed acetylation.The analogous thiocyanatohydrins with a secondary hydroxyl and a tertiary thiocyanate function give a predominance of epoxide from thiocyanatohydrin acetates since the hydrolysis rate of the secondary acetate grouping becomes competitive with that of the tertiary thiocyanate. 

A decisive solvent effect is also observed with other a,/ -epoxy ketones. Specifically, 3jS-hydroxy-16a,17a-epoxypregn-5-en-20-one and its acetate do not react with thiocyanic acid in ether or chloroform. However, the corresponding thiocyanatohydrins are formed by heating an acetic acid solution of the epoxide and potassium thiocyanate. As expected, the ring opening reaction is subject to steric hindrance. For example, 3j6-acetoxy-14f ,15f5-epoxy-5) -card-20(22)-enoIide is inert to thiocyanic acid in chloroform, whereas the 14a,15a-epoxide reacts readily under these conditions.Reactions of 14a,15a-epoxides in the cardenolide series yields isothiocyanatohydrins, e.g., (135), in addition to the normal thiocyanatohydrin, e.g., (134). 

The 5-methyl-5-ethyloxazolidine-2,4-dione may be prepared by reacting methyl ethyl ketone with sodium cyanide and with ammonium thiocyanate followed by desulfurization. This intermediate may also be prepared by condensing a-hydroxy-a-methylbutyramide with ethyl chlorocarbonate or by condensing ethyl a-hydroxy-a-methylbutyrate with urea. Another method described (Traube and Aschar, Ber., 46, 2077-1913) consists in the condensation of ethyl a-hydroxy-a-methylbutyrate with guanidine followed by hydrolysis. 

Compounds in which the anomeric hydroxy group is replaced by a halogen atom are named as glycosyl halides. Pseudohalides (azides, thiocyanates etc.) are named similarly. 

The inner-sphere mechanism is restricted to those complexes containing at least one ligand which can bridge between two metal centers. The commonest examples of such ligands are the halides, hydroxy or oxo groups, amido groups, thiocyanate... 

Supplement (combined with Volume IV) III, 2nd 1929 195-449 Hydroxy-carboxylic acids Carbonic acid, 3. GlycoUic acid, 228. Lactic acid, 261. Tartaric acid, 481. Citric acid, 556. Urea, 42. CyS namide, 74. Thiocyanic acid, 140. 

In acidic aqueous solution, protonation reactions of tetracyanodioxotech-netate(V) give a complicated equilibration, leading to formation of [TcO(OHXCN)4]- and [TcO(H2OXCN)4] . At pH values less than 1, these monomer species are fairly stable, while at pH 2-5, [Tc203(CN)8]4 is formed rapidly. This complicated feature is seen in a plot of /cobsd against pH (Fig. 4). When thiocyanate ion is added to this system at pH 1, it replaces a water molecule or hydroxy group in the coordination site. 

Metabolism of the 2,S -isomers proceeds sequentially hydroxylation at the phenoxy group, hydrolysis of the cyano group, and cleavage of the ester linkage (Coats et al. 1989). Fenvalerate and the IS-isomers yield two ester metabolites in feces from hydroxylation at the 4 - and 2 -phenoxy positions. Other significant metabolites were 3-phenoxybenzoic acid and its hydroxy derivatives from the alcohol moiety, 3-(4-chlorophenyl) isovaleric acid and its hydroxy derivatives from the acid moiety, and thiocyanate and carbon dioxide from the cyano moiety (Ohkawa et al. 1979). A slow elimination rate characterizes fenvalerate and other a-cyano pyrethroids when compared with... 

Zr L = a bidentate hydroxypyranonate or hydroxypyridinonate ligand and X is a halide or alkoxide leaving group (264,265). Replacement of chloride by thiocyanate, pyrazine, or water (in acetonitrile solution) in 3-hydroxy-4-pyranonate or 3-hydroxy-4-pyr-idinonate tin(IV) complexes in all cases follows a two-term rate law of the type... 

The synthesis of 7-amino-3-[[(2,5-dihydro-6-hydroxy-2-methyl-l,2,4-triazin-5-on-3-yl)thio]methyl]-3-cefem-4-carboxylic acid (32.1.2.70) is done in parallel. In order to do this, methylhydrazine is reacted with potassium thiocyanate to give 1-amino-1-methylthiourea... 

In a different study, anthracene, phenanthrene, perylene 93 (Fig. 31), and 2,7-di-tert-butylpyrene underwent regioselective oxidative-substitution reactions with iodine(III) sulfonate reagents in dichloromethane to give the corresponding aryl sulfonate esters. The use of [hydroxy(tosyloxy)iodo]benzene, in conjunction with trimethylsilyl isothiocyanate, led to thiocyanation of the PAH nucleus. 

When the benzene ring of (1) is strongly activated, the milder electrophilic substitution reactions (nitrosation, azo coupling, and thiocyanation) are readily effected in a manner analogous to the naphthalenes <70RCR923>. Nitrosation of the 4- and 5-hydroxy derivatives of (1) occurs at positions 5 and 4, leading to nitroso derivatives that exist predominantly in the quinone monoxime form <74T3839>. 

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