Thiocyano compounds

A related ring closure is also successful in the thiazole series. Treatment of a /3-amino-a,/3-unsaturated ketone with thiocyanogen gave the intermediate thiocyano compound (323) which underwent ring closure to the 2-iminothiazoline derivative (324) (83MI40300). Related reactions are described in Chapter 4.19, and for those involving potassium selenocyanate see Chapter 4.20. 

The properties and uses of thiocyano compounds have been reviewed. Many show toxic effects, mainly dermatitis, which vary considerably in different individuals in addition, tfie alkyl thiocyanates produce degenerative changes in various organs of experimental animals. 

Detection of Thiocyano Compounds. The characterization of the products of thiocyanation does not present many difficulties. Aryl thiocyanates do not rearrange readily upon heating into isothiocyanates (ArN==C=S), and alkyl thiocyanates rearrange only when heated to high temperatures. AUyl thiocyanates and analogous compounds, however, rearrange very readily at elevated temperatiues into isothiocyanates. ... 

By variation of the experimental conditions, a fairly large variety of thiazoles, variously substituted at the 2-position, can be obtained from a-thiocyano ketones. This method was first developed by Tcherniac (1892CB2607). The a-thiocyano ketones are easily obtained from a-halocarbonyl compounds and a metal thiocyanate in alcohol solution. They are very sensitive compounds and isomerize when treated with acids, bases or labile hydrogen and sulfur compounds. 

The cyclization of a-thiocyano ketones (250) in aqueous acid or alkaline solution leads to 2-hydroxythiazoles (251) after dilution with water (Scheme 184). The yields are moderate. With a-thiocyanoacetophenones (252), 4-aryl-2-hydroxythiazoles (254) can be obtained in high yields (Scheme 185). Very early, Arapides (1888LA(249)27> was able to demonstrate the formation of the acyclic compound (253) in the course of this reaction. 

Treatment of the i r-benzyl isoquinolinium bromide with potassium cyanide gave 73. A similar compound was obtained from the ethiodide. Use of potassium thiocyanate in place of potassium cyanide also gave a similar compound. Treatment of 73 or the other analogs with ethanolic picric acid resulted in the liberation of the cyano or thiocyano group to give 2-benzyl- or 2-ethylisoquinolinium picrate. These compounds fail to react as typical Reissert compounds in the presence of phenyllithium or sodium hydride. 

Much of the research on the SbCls-catalyzed halogenation of arenes has focused on the chlorination and bromination of perfluoroalkyl-substituted aromatics [14]. The reaction of organic disulfides with electron-rich aromatic compounds under catalysis with SbCls and AgSbFg affords unsymmetrical aryl sulfides in modest yields [15a]. Electrophilic sulfinylation and sulfonation can be similarly effected by SbCls [15a-c]. Alkyl- and halobenzenes give thiocyano derivatives when treated with a mixture of SbCls and Pb(SCN)2 in CCI4 [16],... 

With other halides, the reaction is conveniently performed by treatment of the alkylthdlium compound with the appropriate copper(I) halide. The product yield is increased by the addition of potassium halide.jhe thallium moiety can also be replaced by other groups, similarly to the arylthallium compounds. The cyano group is introduced by reaction with copper(I) cyanide.lSi the thiocyano group by reaction with potassium and/or copper thiocyanate>5i.i52 and the selenocyano group by treatment with potassium selenocyanate. 

The Tchemiac s synthesis of thiazoles consisting of the rearrangement of a-thiocyano ketones <84CHEC-I(6)299> has been used in the preparation of bisthiazolyl compounds (273) starting from diaminoalkanes <90JPR723>. The reaction cannot be applied to a-thiocyanato-/S-dicarbonyl deriva-... 

Other synthetic terpenoid derivatives prepared as potential insecticides include further thiocyanato compounds among which is longifolyl thiocyano-acetate [668]. Relatively little attention would, however, seem to have been paid to the preparation of terpenoid organophosphorus compounds as potential insecticides or of terpenoid organotin compounds as potential fungicides. 

Thiocyanogen reacts with aromatic compounds that are highly susceptible to substitution with the introduction of a thiocyano group. Reactions reported thus far are mainly with phenols of the benzene and naphthalene series and with primary, secondary, or tertiary amines of the... 

Thio-L-rhamnofuranose (27) was obtained by triflate displacement at C-4 of the h-talo-configurated pyianose derivative (26) with KSCN in DMF and subsequent reduction of the thiocyanate group and acetolysis/deacetylation as indicated in Scheme S." When similar displacements were attempted with derivatives of methyl 6-deoxy-a-D-mannopyranoside, a 2 1 mixture of 4-thiocyano sugars (32) and (33) was produced from the dihydroxy-p-nitrobenzenesulfonate (28) in S2% combined yield however, compounds (29)-(31) underwent solvolysis and/or decomposition under the reaction conditirms. ... 

Benzothiazole, a compound with a rubbery, burnt odor, was identified in samples from both sources (Fig. 4). It was discovered that the paper mold-inhibitor [2-(thiocyano-methylthio)-benzothiazole] was susceptible to thermal degrada-... 

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