Thiourea monofunctional

Scheme 6.55 Design principle of amine-functionalized bifunctional thiourea organocatalysts derived from privileged monofunctional thiourea 9 cooperating with an amine base additive (A) and basic bifunctional mode of action of chiral amine...

Apart from the increased catalytic efficiency, this structure design produced two positive side effects. In contrast to monofunctional (thio)ureas, which exhibit low solubility in nonpolar solvents due to intermolecular hydrogen-bonding association, tertiary amine thioureas of type 12 revealed intramolecular hydrogen bonding between the amine group and the amide protons making these (thio)ureas soluble in nonpolar reaction media such as toluene. The analysis of the X-ray crystal-... 

Scheme 6.108 Proposed mechanistic picture for the 106-catalyzed MBH reaction affording (R)-adducts (A) and monofunctional thiourea 107 displaying low catalytic activity (B).

A second mechanism of inactivation might be the reaction of sulfur-containing biomolecules with the cis-Pt-DNA monoadducts (product 1 in Fig. 4), which prevents those from rearranging to toxic bifunctional adducts. Supportive for such a mechanism is the observation that GSH can be cross-linked to DNA by cis-Pt (41,41a) and [Pt(en)Cl2] (74), and that cysteine can be cross-linked to d-Guo by cis-Pt (77). Furthermore, cis-Pt-DNA monoadducts can be experimentally quenched with thiourea, which reduces drug toxicity (82, 83). trans-Pt also yields monofunctional adducts after reaction with DNA, and these rearrange somewhat slower than does cis-Pt into bifunctional adducts (41,84), clearly for sterical reasons. The relatively long-living monofunctional adducts react efficiently with GSH and proteins (41 a, 84-86). 

Molecular Connectivity- Kow Relationships Kier and Hall [34] have analyzed the correlation between K0w and various MCIs for hydrocarbons and monofunctional alcohols, ethers, ketones, acids, esters, and amines. Analogous relationships have been studied by Finizio et al. [35] for substituted s-triazines and by Govers et al. [36] for thioureas. 

The /V-ethylpyrazinium 36e and 8-ethylpteridinium salts 40d which show, as we have seen (see Tables I and III), some tendency to undergo a diaddition with monofunctional nucleophiles, are also able to react with 1,3-bifunctional nucleophilic reagents to give cyclization products. Thus, reactions of pyrazinium 36e and pteridinium 40d salts with thioureas afford... 

Thiourea behaves as a monofunctional compound in its reaction with o-chloromethylbenzoyl chloride but A. TV -thioureas give rise to seven-membered rings (see Swtion III.l). A fused pytrol-2-one ring may also be synthesized by treating o-A -acylbenzamides with sodium hydride and then with butyl-lithium at — 78°C the lithio-oxy derivative formed is then quenched with hydrochloric acid after standing for 2h. 

Variations in monofunctional adduct lifetimes were also invoked to explain the relative ratios of different platinum adducts formed by cis-DDP on DNA. When the reaction of PH][Pt(en)Cl2] with DNA was allowed to occur in the presence of thiourea, subsequent enzymatic digestion of the... 

Apart from the reports mentioned above, there are sustainable monofunctional thioureas that successfully induce chirality. In 2007, Jacobsen and coworkers reported the enantioselective Pictet-Spengler cyclisation of hydroigrlactams. Utilising as little as 0.1 mol% of thiourea 10, indolizinone and quinolizinone products were afforded in high yields and high enan-tioselectivities (Scheme 19.14) via a counterion transition state. ... 

NMR spectroscopy indicates a dynamic equilibrium of rotamers of the thiourea in complex ions such as [PtCl(diamine)(monofunctional thiourea)] Dynamic processes in platinum(II)-adenosine complexes have been investigated and the Pt NMR spectra recorded.Variable temperature NMR spectroscopy shows restricted rotation of the NO group in [PtCl3(4-X-C6H4NO)] . The intramolecular conformational exchange thermodynamics of a5 -[PtCl2 l,T-(CiiH23SeC5H4-ri )2Fe ] have been determined. 

We must stress the fact that the formation of clathrates is not specific for hydrocarbons. A large number of monofunctional and difunctional compounds are known which form clathrates with urea or thiourea. 

In here, at least one Y is hydrolyzable group, and X is a functional group such as iodine, sulfur, thiocyanate, thiourea, cyanide, etc., which is called bifunctional silane. When X is a hydrogen, it is called monofunctional silane. Two moles of 3-chloropropyltrialkoxysilanes react with one mole of disodium tetrasulphide produces bis-type bifimctional silane, which is called bis(triethoxysilylpropyl)tetrasulfide (TESPT) [171,172]. 

MichaeU-Henry Reaction Liu et al. and Xie et al. independently found that tertiary amine-thioureas could stereoselectively promote the addition of diethyl a-aminomalonate-derived azomethine ylides to nitroolefms, affording Michael adducts other than dipolar cycloaddition adducts as the major products. Using monofunctional chiral thioureas 140d instead of tertiary amine-thiourea catalysts, Liu et al. successfully developed a three-component [3-1-2] dipolar cycloaddition of benzaldehydes 3, diethyl a-aminomalonates 45a, and nitrostyrenes 165, resulting directly in the enantioenriched pyrrolidines 208 as the only products (Scheme 2.56) [81a] while Xie et al. efficiently converted the Michael adducts 210 to pyrrolidines 208 in high yield and maintained ee by the use of 30 equiv of 2,2,2-trifluoroethanol as the additive (Scheme 2.56) [81b]. 

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