Thiourea guanidinium

Thiocyanate has been found to be competitive with ethanol but noncompetitive with NAD (398). At concentrations less than 0.3 M the inhibition is reversible but at higher concentrations irreversible. Low concentrations of urea (398,450) inhibit YADH noncompetitively with respect to NAD, NADH, alcohol, and aldehyde. Higher concentrations inhibit the enzyme irreversibly (Section III,C,8). Thiourea, guanidinium salts (398), phenylisopropyl hydrazine (258), and canavanine (451) are also inhibitors of YADH. 

Heterocyclic rings can be produced from the reaction of a chalcone 203 under basic conditions with urea or thiourea, generating the corresponding diaryl guanidinium structure 204a or 204b as displayed in Scheme 56 by Kidwai and... 

Figure 6.55 Uncharged tris-thiourea 190 without guanidinium moiety and charged guanidinium structure 191 without a thiourea group appeared catalytically inactive in the Henry reaction of cyclohexane carboxaldehyde with nitromethane, while guanidine-thiourea 183 gave 99% yield and 95% ee under identical (optimized) conditions.

Scheme 4.2 Synthesis of chiral guanidinium hosts starting from chiral amino acids either via cycli-sation of an open chain triamine or unsymmetrically substituted thiourea.29...

A bis(isothiocyanate) was treated with a diamine in the ring-closure step. The resulting cyclic bis(thiourea) was converted into the bis(guanidinium)-containing macrocycle. 

Closely related to the just-discussed transformation of sugar thiolactams into amidines is the preparation392 of the cyclic guanidinium glycomimetics 241 and 242 from the cyclic thiourea precursor 239. Replacement of the... 

Beer. P.D. Drew, M.G.B. Smith. D.K. Selective electrochemical recognition of bidentate anionic guests in competitive solvents using novel ferrocenyl thiourea and guanidinium receptors. J. Organomet. Chem. 1997. 

Figure 3 Receptors containing thiourea (7), urea (8), guanidinium (9), or acylguanidinium (10) units with their respective binding constants to 5 or 6. The thermodynamic parameters to carboxylate binding are also given.

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