Thiamides

The 1,3-dipolar cycloaddition reactions of several other mesoionic heterocycles have been investigated since Potts review (1). Kato et al. (113,114,123) found that the l,3-thiazohum-5-olate (358) ring system affords low yields or complex reaction mixtures with benzocyclopropene (113), benzocyclobutadiene (114), and tropone (123). Likewise, Vedejs and Wilde (209) isolated in low yields a cycloadduct of 358d with thiopivaldehyde, along with a ring-opened thiamide. Also, 1,3-thiazo-lium-5-olate 359 reacts with thiopivaldehyde to give 360 (209). 

Aromatic amides, sometimes referred to as aryiamides, exhibit the same relationship. Note the relationship of benzoic acid Cg H5 COOH with benzamide Q H5 CONH2. Thiamides are derived from amides in which there is substitution of the O atom by a sulfur atom. Thus, acetamide NHa- CO- CH3, becomes thiacetamide NH2- CS- CH3 or acetanilide C6 H5- NH- CO- CH3 becomes thiacetanilide C6 H5- NH- CS- CH3. Sulfonamides arc derived from the sulfonic acids. Thus, bcnzcnc-sulfonic acid Cg H5 SO2- OH becomes benzene-sulfonamide Cg Hs- SOv NH2. See also Sulfonamide Drugs. 

Isonicotinic thiamide (270)127 is reduced as other thiamides319 the primary reduction product, the grem-aminothiol, R-CH(SH)NH2, is fairly stable in cold acidic solution, but decomposes on evaporation of the solvent to hydrogen sulfide and the pyridine-4-carbaldehyde. 

The 4-pyridinecarboxylic acids [440, 441], 2-carboxythiazoles [445] and 2-carboxyi-midazoles [436, 446], and their esters amides, and thiamides [392, 447-450] are reduced in this way. The corresponding hydrazides [451] and hydroxamic acids [51] are reduced to the amides in the first step and then further reduced. When the activating group in pyridine is in the 3-position the reduction may take place in the nucleus, depending on pH. 

Reactivity and spectroscopic properties of N-substituted secondary thioamiodes. Spychala reported the results of an interesting study in 2003 involving proton complexes based on thiamide ligation. The author utihzed both HSQC and... 

Reactions of thoiminium salts, generated in situ from thioamides and methyl triflate (MeOTf), with two different alkylmetals such as alkynyllithiums and alkylmagnesium bromides have been studied. The two different organometallic reagents have been nucleophilically introduced to the carbon atom of the thiocarbonyl group of thiamides to afford tertiary propargylamines in one-pot procedure (Scheme 36). ... 

Dicarboxylic acid imides from dicarboxylic acid amide esters Dicarboxylic acid monothioimides from dicarboxylic acid thiamide esters... 

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