Bis-thioureas

Compound 129, with R=Ph, p-MeCsH4, p-MeOC H, p-EtOC H, and 2-furyl, was obtained in 70 to 80% yield when p-phenylene bis-thiourea was heated with iodine and p-AcCaHjE, accxtrding to Method B (741). 

LOPQIQ l,3-Bis(thiourea)triiodonium thiourea-diiodine diiodine triiodide 2.437 3.168 171.59 I... 

Since 1980 the interest in this reaction increased because enantiospecificity was introduced and much more valuable products could be made. A wide variety of ligands was tested, such as chiral dipyridines, phenanthrolines, diphosphines, aminoalcohols, bis-oxazolines, bis-oxazolines with a third donor atom in the centre, bis-thioureas, diamines, etc [33], In 1981 the highest e.e. reported was still only 20%. For many years the best results were obtained with chiral diimines and phenanthrolines but e.e. s were below 70% [34], Pfaltz introduced bis-oxazolines for this reaction and obtained e.e. s as high as 91% [35] in 1991. 

Nagasawa and co-worker, in 2004, introduced the first bis-thiourea-type catalyst... 

P-Amino carbonyl compounds containing an a-atkyUdene group are densely functionalized materials, which are widely applied in the synthesis of medicinal reagents and natural products [265]. These products are usually prepared through the classic aza-Morita-Baylis-Hillman reaction [176, 177] of activated imines and electron-deficient alkenes catalyzed by tertiary amines or phosphines. Chen and co-workers, in 2008, identified bis-thiourea 106 as a suitable catalyst for the... 

On the basis of this concept, bis-urea (13) and bis-thioureas (14-18) were synthesized and their binding with dihydrogenphosphate (H2PO4) and various other anions in dimethyl sulfoxide (DMSO) was investigated by H NMR spectroscopy. Stability constants, /r,, for the 1 1 complexes are given in Table 1, together with those for the 1 1 complexes with )V,A/ -dimethylurea (19) and NJ -dimethylthiourea (20). ... 

Figure 5. Suggested structure of 1 1 complex between dihydrogenphosphate (H2PO4) and bis-urea (X = O) and bis-thiourea (X = S) receptors.

Ion-Selective Electrodes based on Bis-Thiourea Receptors. Bis-thiourea derivatives 14, 15, and 17, which have a good membrane solubility, sufficient lipophilicity to prevent leaching into the aqueous sample solution, and a low tendency for self-aggregation in nonpolar solvents, were incorporated into PVC matrix liquid membranes for ISEs. While membrane electrodes based on the dibutyl derivative 14 gave a phosphate response almost identical to that of a conventional anion-exchanger electrode, a membrane electrode based on the phenyl-substituted bis-thiourea 15 exhibited a slightly improved phosphate response, which seems to be the result of improved complexation of phosphate in the sensor membrane. 

For the bis(thiourea) iodine(I) cation,101 in the iodide salt, there is a linear S—I—S arrangement with the I—S distance of 2.629 A. The complex cation102... 

Intramolecular cyclization of bis(amides) 106 (X = 0 R1, R2 = Me, Ph, 4-BrC6H4) (Scheme 20) on treatment with Ph3PBr2 in the presence of triethylamine gave the corresponding benzoxadiazepines 107 in 52-74% yields <1988M1279>. Similarly, reaction of bis(thioureas) 106 (X = S R1 = R2 = NHBu-/, arylamino) with I2/KI/KOH system in ethanol afforded in 68-79% yields the benzothiadiazepines 107, existing as exocyclic bis(imino) tautomers... 

MI139, 2004MI773>. Bis(thioureas) [CH2NHC(S)NHR]2 (R = allyl, Ph, benzyl) with ethylene instead of 1,2-phenylene linker cyclized to thiadiazepines 108 in the presence of tetracyanoethylene in THF at ambient temperature <2004ZNB910> or neat on conventional heating or under microwave irradiation <2003HAG535>. 

Tozawa, T., Misawa, Y., Tokita, S., Kubo, Y., A regioselectively bis (thiourea)-substituted dibenzo-diaza-30-crown-10 a new strategy for the development of multi-site receptors. Tetrahedron Lett. 2000, 41, 5219-5223. 

The C2-symmetric chiral bis-thiourea catalyst 78 mediated the addition of cyclohexanone to a range of activated aldehydes in the presence of DMAP, or imida-... 

Table 5.8 Chiral bis-thiourea and DMAP-mediated MBH reaction of cyclohexenone and aldehydes.

Nagasawa and co-workers reported the use of a chiral bis-thiourea catalyst (108) for the asymmetric MBH reactions of cyclohexenone with aldehydes [95]. Since others had already shown that thioureas form hydrogen bonds with both aldehydes and enones, it was hypothesized that the inclusion of two thiourea moieties in close proximity on a chiral scaffold would organize the two partners of the MBH reaction and lead to enantiofacial selectivity. Initial studies showed that the achiral 3,5-bis-(trifluoromethyl)phenyl-substituted urea increased the rate of MBH reaction between benzaldehyde and cyclohexenone. These authors then showed that chiral 1,2-cyclohexyldiamine-linked bis-thiourea catalyst 108, used at 40 mol% loading in the presence of 40 mol% DMAP, promoted the MBH reactions of cyclohexenone with various aliphatic and aromatic aldehydes (40) to produce allylic alcohols in moderate to high yields (33-99%) and variable enantio-selectivities (19-90% ee Table 6.33). 

Table 6.33 Bis-thiourea-catalyzed Morita-Baylis-Hillman reactions of cyclic enones.

Tellurium dithiocyanate is known only in the form of its yellow complexes with thioureas. These complexes were prepared from bis[thiourea]tellurium dihalides and potassium or ammonium thiocyanate in aqueous or methanolic media. 

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