Aminolysis complexes

Surfactants have also been of interest for their ability to support reactions in normally inhospitable environments. Reactions such as hydrolysis, aminolysis, solvolysis, and, in inorganic chemistry, of aquation of complex ions, may be retarded, accelerated, or differently sensitive to catalysts relative to the behavior in ordinary solutions (see Refs. 205 and 206 for reviews). The acid-base chemistry in micellar solutions has been investigated by Drummond and co-workers [207]. A useful model has been the pseudophase model [206-209] in which reactants are either in solution or solubilized in micelles and partition between the two as though two distinct phases were involved. In inverse micelles in nonpolar media, water is concentrated in the micellar core and reactions in the micelle may be greatly accelerated [206, 210]. The confining environment of a solubilized reactant may lead to stereochemical consequences as in photodimerization reactions in micelles [211] or vesicles [212] or in the generation of radical pairs [213]. 

In 1965, Breslow and Chipman discovered that zinc or nickel ion complexes of (E)-2-pyridinecarbaldehyde oxime (5) are remarkably active catalyst for the hydrolysis of 8-acetoxyquinoline 5-sulfonate l2). Some years later, Sigman and Jorgensen showed that the zinc ion complex of N-(2-hydroxyethyl)ethylenediamine (3) is very active in the transesterification from p-nitrophenyl picolinate (7)13). In the latter case, noteworthy is a change of the reaction mode at the aminolysis in the absence of zinc ion to the alcoholysis in the presence of zinc ion. Thus, the zinc ion in the complex greatly enhances the nucleophilic activity of the hydroxy group of 3. In search for more powerful complexes for the release of p-nitrophenol from 7, we examined the activities of the metal ion complexes of ligand 2-72 14,15). 

Very recently, even examples of donor-stabilized bissilylene complexes have been introduced. For instance, the two cyclic systems 13 and 14 are prepared by an aminolysis reaction of the respective bis(chloro)silyl complexes. The x-ray structure analysis of 13 has been performed [39]. 

The generalized application of the aminolysis of halophosphanes has been the method of choice for the preparation of a wide variety of chiral phosphinous amides by starting from enantioenriched primary amines [36]. The aminolysis reaction occurs efficiently even when the halophosphane is placed in the coordination sphere of a metal, as in the palladium and platinum complexes of the type ds-M(Ph2PCl2)2Cl (M=Pd, Pt) [37,38]. 

Although hydrolysis as well as other nucleophilic reactions of A-acylazoles (alcoholysis, aminolysis etc.) most likely follow the addition-elimination (AE) mechanism, there are indications that more complex mechanisms must be taken into account for hydrolysis under specific structural conditions. For example, for neutral hydrolysis of imidazolides with increasing steric shielding of the carbonyl group by one, two, and three... 

A comprehensive study of aminolysis reactions involving dinuclear platinum(II)-hydroxo complexes has been described.176 Treatment of the di-/i-hydroxo complexes of the type [Pt2-(/i-OH)2(L2)2]2+ with an excess of aryl amine RNH2 (L = PPh3, R = Ph, p-tolyl, /)-Bu Cr,I I4,... 

Indeed, nucleophilic attack at Ca is the most widely observed single reaction of Fischer carbenes. Substituent substitution is favored when one of the substituents on the carbene carbon is a good leaving group, e.g., halide, alkoxide, etc. Aminolysis of complex 41 typifies this mode of reaction (17),... 

For the heavier alkaline earth elements the characterized compounds are octahedral monomers, dimers, or separated-ion species. The complexes M(SR)2 (M=Ca, Sr, Ba) have been obtained by aminolysis and proved to be soluble in solvents such as py these compounds decompose rather cleanly to their metal sulfides.86 The monomeric species include [M(EMes )2(thf)4] (M=Ca, Sr, Ba E=S, Se),87 89 [Ca(SC6F5)2(py)4],90 [Ca(SMes )2(18-crown-6)] thf,90 or [Ba(Se-Trip)2(18-crown-6)].87 Only a dimeric barium derivative, [Ba(SeTrip) (py)3(thf)]2, has been described.87 For these elements separated ion-triple species, such as [M(18-crown-6)(hmpa)2][EMes ]2 (M=Ca, Sr, Ba E=S, Se)87,88,91 or contact/separated ion-triple species as [Ba(SMes )(18-crown-6)(hmpa)][SMes ] have been reported.91... 

Three alternative mechanisms have been mentioned in the literature. Reduction of C02 to CO followed by carbonylation of dimethylamine was ruled out by Haynes et al. [3] for RhCl(PPh3)3 because no carbonyl complexes were detected. Aminolysis of formate complexes (Eq. (14)) was proposed by Kudo et al. [69], but strong evidence has not been obtained. Finally, C02 is known to react with the amine to produce a carbamate salt (Eq. (15)), and it is possible that the pathway to the formamide is by hydrogenation of the carbamate rather than of the C02. 

Ti(OPr1)4-mediated nucleophilic ring opening of 2,3-epoxy-alcohol with primary amine requires more rigorous conditions, and the product is a complex mixture. Lin and Zeng22 found that this problem could be overcome and moderate to good yields could be obtained under weak base conditions by in situ /V-acylation of the aminolysis product with benzoyl chloride. 

Figure 5. Theozymes for ester aminolysis. (a) Ether theozyme (bold) complexed to the direct displacement transition state for aminolysis. (b) DME theozyme (bold) complexed to the direct displacement transition state for aminolysis.

Table VI lists a number of dipeptide ester complexes prepared via aminolysis in Me2SO and isolated using ion-exchange chromatography many others have been obtained from similar syntheses. Crystal structures are available for A-[Co(en)2((S)-Ala-CR)-Phe)]Br3 H20 (26), obtained from reaction of A-[Co(en)2((S)-AlaOMe]3+ with (i )-PheOMe and acid hydrolysis (Fig. 1), and for A-[Co(en)2((S)-Leu-(S)-Leu OMe)]Cl3 4H20 (24), A-[Co(en)2((S,fl)-Ala-(S)-ValOMe)](C104)3 (24), and /3-[Co(trien)(Gly-GlyOEt)](C104)3 H20 (10). These show considerable variation in chelate 0-Ci-C2-N dihedral angles (0-35°) (10) and it remains to be seen whether this property is important to epimerization (at C2) in these species.

The [lyridine used in the submitters procedures apparently ri Mcts with the sulfuryl chloride to form an intermediate qmiteriiary pyridiuiurn complex which undergoes aminolysis III yield the sulfamide." However, in many instances the pyridine may be replaced by an e( uival( iit (piantity of the primary... 

The cyclodextrin-supported cleavage of 1,3-oxathianes with IBX (cf Scheme 76, Section 8.11.6.4.6) <2006SC3771>, as well as the copper-catalyzed aminolysis of 1,3-dithianes <2006OL2547> has been published. l,3-Dioxane-2-ones readily undergo a Grob fragmentation (Equation 100) <2006CC4303>. This reaction is catalyzed by Ni- (24-99% yield) or by Pd-complexes (42-93% yield). 

However, the azide-based protocol often has problems with the formation of byproducts under both azide formation and subsequent reduction. 388 Therefore, mainly aminolysis is used. Glycosylamines are prepared from GlcNAc, GlcNAc2, Glc, maltotriose, mal-toheptaose, and di- and triantenneary complex glycans, isolated from asialofetuin by preparative hydrazinolysis. A modification of the method by Likhosherstov is also employed. 379 ... 

The Pd-catalyzed reaction of 5-vinyl-l,3-oxazolidin-2-ones 260 at 65-70°C and 65 atm of CO in ethanol gave 5-lactams 263 in fairly good to high yields (Scheme 38).As Scheme 38 illustrates, this decarboxylative carbonylation reaction is likely to involve (i) the cleavage of the allylic C-O bond of 260 to form tr-allyl-Pd complex syn-2(A, (ii) isomerization to anti-2(A, (iii) decarboxylation forming 7r-allyl-Pd-amine complex 262, and (iv) CO insertion to 262 followed by aminolysis to yield 5-lactam 263. 

---