Amino alcohol urea derivative

The addition of anilines to styrene oxide was reported to also proceed in the presence of 10mol% 37 affording the corresponding P-amino alcohols 1-5 in yields ranging from 75% to 92% (Scheme 6.37). Additionally, urea derivative 37 (20mol% loading) was found to catalyze the addition of aniline (2.0 equiv.) to ( )-stilbene oxide (92% yield 5.9 d 30°C), the addition of thiophenol (2.0 equiv.) to 2-methoxy styrene oxide (85% 20h rt), and the alcoholysis of 4-methoxy styrene oxide with benzyl alcohol (2.0 equiv.) affording the respective P-alkoxy alcohol (82% 20h rt). 

Thio)urea Catalysts Derived from Chiral Amino Alcohols... 

Ricci and co-workers introduced a new class of amino- alcohol- based thiourea derivatives, which were easily accessible in a one-step coupling reaction in nearly quanitative yield from the commercially available chiral amino alcohols and 3,5-bis(trifluoromethyl)phenyl isothiocyanate or isocyanate, respectively (Figure 6.45) [307]. The screening of (thio)urea derivatives 137-140 in the enantioselective Friedel-Crafts reaction of indole with trans-P-nitrostyrene at 20 °C in toluene demonstrated (lR,2S)-cis-l-amino-2-indanol-derived thiourea 139 to be the most active catalyst regarding conversion (95% conv./60h) as well as stereoinduction (35% ee), while the canditates 137, 138, and the urea derivative 140 displayed a lower accelerating effect and poorer asymmetric induction (Figure 6.45). The uncatalyzed reference reaction performed under otherwise identical conditions showed 17% conversion in 65 h reaction time. 

Oxazincs are formed starting from nitriles and diols. 1,3-Amino alcohols react with phosgene or urea derivatives to give l,3-oxazin-2-ones. -Amino acids are converted to... 

In amino acid and peptide chemistry, the di-ferf-butyl dicarbonate (BocaO) is an extensively used reagent for the clean and rapid Boc-protection of amine functionalities.It is also an efficient ferf-butoxycarbonylating agent for alcohols, thiols, and carbon nucleophiles, and it has been used for the conversion of amines into isocyanates, carbamates, and urea derivatives.The reaction of amino acids with chloroformates to produce N-urethane-protected amino acids if not performed under optimal conditions is accompanied by the formation of N-protected oligomers this has been well documented in the case of and... 

Syntheses of this type are from urea, thiourea, and amidine and guanidine derivatives. Ureas give tetrahydro-l,3,5-triazin-2-ones on reaction with a primary amine (1 equiv.) and aqueous formaldehyde (2-30 equiv.). In general, alkyl and aryl amines, unsaturated amines, amino alcohols, and a-amino esters form triazinone derivatives (Equation (43)). Methyl and benzyl have proven to be the most useful urea substituents with respect to high yields and product solubility. N,N -Dicyclohexyl- and A,A -diphenyl-urea gave poor yields of triazinone <90TL2109>. 

The following compounds are used as inhibitors in acid solutions amines, amino-imidazolines, amino- and nitrophenols, aminotriazole, aldehydes, bezothiazol, dibenzyl sulfoxide, dithiophos-phoric acids, guanidine derivatives, ureas, phosphonium salts, sulfonium salts, sulfonic acids, thio-ethers, thioureas, and thiocarbanoyl disulfides. Amino alcohols, aminobenzimidazole, benzoates, quinoline derivatives, cinnamates, fatty amines, polyether amines, silicates, and triazoles are used as inhibitors in neutral or weakly alkaline solutions, while for strongly alkaline solutions, aldehydes and fatty amines are used. 

The use of chiral diamines in Schiff bases complexes allowed exploration of the powder SHG efficiency of crystalline materials based on this class of NLO chromophores, otherwise inactive because of the almost always crystal centrosymmetry. Relatively high powder SHG efficiency (up to 13 times that of urea) has been achieved in the case of the (l/ ,2/ )-(+)-l,2-diphenylethylenediamine Ni derivative [108]. Analogous Zn complexes using the chiral (R)-(-l-)-l-phenylethylamine have given appreciable powder SHG efficiencies [109]. This strategy has been extended using a series of chiral amino alcohols [110] and amino acids [111] to obtain noncentrosymmetric crystals based on Sn derivatives, with an attempt to correlate their SHG efficiencies with the molecular chirality. 

It seems appropriate to remember that there are also other classes of molecules that are catalytically active thanks to one of the mentioned mechanisms (ureas, thioureas, phosphoric acids, etc.) as well as molecules with two or more different functional sites (bifunctional organocatalysts) one of which is often an alcoholic/phenolic/carbojqrlic group (amino-alcohols, aminoacids, proline derivatives, aminophenols, etc.) they will be not discussed in this chapter because they have already been examined in previous chapters or because they contain nonsustainable elements. 

After decomposition of the unstable carbamic acid to the initial amino alcohol, the latter reacts with already formed isocyanate, resulting in urea derivatives. This side reaction distorts the perfect stoichiometry of the AB-type polymerization, and consequently, limits the molecular weight of the polymer. 

As far as the volumetric properties are concerned, values at 25°C have been reported for alcohols(31,55-59a), ethers(11b,34, 58,60,61), amines(34,57,62-64), esters(11b,58), ketones(llb,36,58), amides(36,37,63,65), carboxylic acids(62a,b,67), hydroxycarboxylic acids(66c), polycarboxylic acids(66d), polyols(31,42 56,59b), pyri-dines and others unsaturated heterocyclic compounds containing ni-trogen(38), ethylene glycol derivatives(11a,61,68-70), carbohydra-tes(72-74), urea and derivatives(44,74,75) polyamines(76,77a) amino-alcohols and aminoethers(77b), polyethers(6°,61,77c), alkylhalides (61), benzene and derivatives(llc,26c), Moreover the behaviour of the functions = f(T) has been studied for alcohols(10,12,55,56) and polyols(12,55,56,68,78), ethers(12) and polyethers(llb,12,68), ketones and esters(11b), ethylene glycol derivatives(11a,68,71,78). Compressibility data at 25°C have been calculated from ultrasonic velocity measurements for ethers(79), amines(62), alcohols(79-82), polyols(79), ethylene glycol derivatives(68,71), polyethers(68,74, 79) urea and derivatives(74), carbohydrates(72,74). Finally some investigations about the influence of various types of non-electrolytes on the temperature of maximum density(82b,83) and the adiabatic compressibility minimum(84) of water are to be remembered. 

Moreover, the same authors employed a closely related organocatalyst and the corresponding urea derivative to promote the enantioselective dynamic kinetic resolution of azalactones with allylic alcohol. In this case of substrates, the urea derivatives proved to be superior to their thiourea analogues and, most usefully, these catalysts were insensitive to the steric bulk of the amino acid residue, allowing alanine-, methionine- and phenylalanine-derived azalactones to undergo dynamic kinetic resolution with unprecedented levels of enantioselectivity, as shown in Scheme 9.4. Furthermore, the compatibility of these catalysts with thiol nucleophiles was exploited in the first enantioselective catalytic dynamic kinetic resolution of azalactones by thiolysis to furnish enantioenriched amino acid thioesters of potential use with moderate enantioselectivities (<64% ee). 

Some commercial durable antistatic finishes have been Hsted in Table 3 (98). Early patents suggest that amino resins (qv) can impart both antisHp and antistatic properties to nylon, acryUc, and polyester fabrics. CycHc polyurethanes, water-soluble amine salts cross-linked with styrene, and water-soluble amine salts of sulfonated polystyrene have been claimed to confer durable antistatic protection. Later patents included dibydroxyethyl sulfone [2580-77-0] hydroxyalkylated cellulose or starch, poly(vinyl alcohol) [9002-86-2] cross-linked with dimethylolethylene urea, chlorotria2ine derivatives, and epoxy-based products. Other patents claim the use of various acryUc polymers and copolymers. Essentially, durable antistats are polyelectrolytes, and the majority of usehil products involve variations of cross-linked polyamines containing polyethoxy segments (92,99—101). 

Amphoteric compounds such as amino acids can be resolved as acid or amine forms after deriving corresponding esters or N-acyl compounds. Racemic alcohols and amines are also resolved by use of optically active isocyanates, where the alcohols and amines are derived the corresponding diastereomeric urethanes or ureas. 

There are several types of chiral derivatizing reagents commonly used depending on the functional group involved. For amines, the formation of an amide from reaction with an acyl halide [147,148], chloroformate reaction to form a carbamate [149], and reaction with isocyanate to form the corresponding urea are common reactions [150]. Carboxyl groups can be effectively esterified with chiral alcohols [151-153]. Isocynates have been used as reagents for enantiomer separation of amino acids, iV-methylamino acids, and 3-hydroxy acids [154]. In addition to the above-mentioned reactions, many others have been used in the formation of derivatives for use on a variety of packed and capillary columns. For a more comprehensive list, refer to References 155-159. 

Figure 6.2. (Upper panel) The four major classes of organic osmolytes (I) sugars and polyhydric alcohols (polyols) (II) amino acids and amino acid derivatives (III) methylated ammonium and sulfonium compounds and (IV) urea. (Figure modified after Somero and Yancey, 1997.) (Lower panel) Structures of charged osmolytes accumulated in extremely halophilic archaea (after Martin et al., 1999). Note that these osmolytes commonly represent a type of organic osmolyte that is found in many bacteria or eukaryotes to which a charged group has been attached. Typically, the charged group is anionic, for example, a phosphate or a carboxylate group.

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