Epoxidations amine catalyzed

Epoxidation.1 This combination is known to oxidatively cleave double bonds but to effect epoxidation when catalyzed by a metalloporphyrin. Epoxidation of alkenes can also be effected by catalysis with a simple amine. The choice of the amine depends on the olefin. N,N-Dimethylethylenediamine is the most efficient ligand for epoxidation of a 1-alkene (68% yield). Pyridine is the best ligand for epoxidation of stilbene (93%), and imidazole is preferred for epoxidation of QH5CH=CHCH, (71% yield). 

The amine-catalyzed mercaptan-epoxide reaction (Equation 4) proceeds exothermally at room temperature (27. 28). The order of average relative nucleophile-displacement rates (Table II) further suggests that mercaptans react significantly faster than amines and that the addition of the mercaptlde (RS ) ion to the epoxide group is the rate determining step (30). 

Carree, F. Gil, R. Collin, J. (2005) Enantioselective ring opening of meso-epoxides by aromatic amines catalyzed by lanthanide iodo binaphtholates., Org. Lett., 7 1023-1026. 

Kureshy, R. 1. Singh, S. Khan, N. H. Abdi, S. H. R. Agrawal, S. Mayani, V. J. Jasra, R. V. (2006) Microwave-assisted asymmetric ring opening of meso-epoxides with aromatic amines catalyzed by a Ti-S-(—)-BlNOL complex.. Tetrahedron Lett., 47 5277- 5279. 

Gao, B. Wen, Y. Yang, Z. Huang, X. Liu, X. Feng X. (2008) Asymmetric ring opening of meso-Epoxides with aromatic amines catalyzed by a new proline-based N,N -dioxide-indium tris (triflate) complex,/t/v. Synth. Catal, 350 385- 390. 

Armstrong, A. Amine-catalyzed Epoxidation of Alkenes A New Mechanism for the Activation of Oxone. Angew. Chem. Int Ed. 2004, 43, 1460-1462. 

Fig. 4. Zeroth-order graph of a stoichiometric anhydride/epoxide tertiary amine-catalyzed copolymerization at 80 °C...

Kishimoto Y, Ogawa I (2004) Amine-catalyzed, one-pot coproduction of dialkyl carbonates and 1, 2-diols from epoxides, alcohols, and carbon dioxide. Ind Eng Chem Res 43(26) 8155-8162... 

An impressive addition to the now extensive repertoire of amine-catalyzed reactions is the epoxidation of a-/ -unsaturated aldehydes described by Jorgensen and co-workers, catalyzed by proline-derivative 31 (Fig. 12.11) [77, 78]. As with related processes, this chemistry likely proceeds via activation of the unsaturated alde-... 

General Procedure for Chiral Amine-Catalyzed Epoxidations of Enals with H202 [50] (p. 104)... 

Amine-Catalyzed Epoxidation of E-Cinnamaldehyde with Hydrogen Peroxide [62] (p. 418)... 

Vinyl epoxides can also be used as substrates for formation of optically active allyl amines catalyzed by the same type of chiral palladium complexes as in Eq. (10). By reaction of simple vinyl epoxides with phthalimide as the nitrogen source in the presence of the chiral palladium complexes as the catalyst, very high ee (> 98 %) and regioselectivity (> 97 %) were obtained [26]. A variety of different applications of the use of the palladium-catalyzed approach for the formation of allyl amines and the use of this in total synthesis has been pursued by several research groups, and further details can be obtained in a review by Trost et al. [19d]. 

The polyetherification of epoxide groups catalyzed by tertiary amines is characterized by formation of polymers of low degree of polymerization, a part of which is nitrogen-free (cf. Berger and Lohse, Section 4.5). 

Amino alcohols. Epoxide opening by amines catalyzed by SmClj is regioselective and stereoselective. The nucleophiles attack from the less substituted carbon atoms. 

Amine-catalyzed epoxidation is a relatively new area, and the active species is thought to be an ammonium peroxymonosulfate salt which acts as a phase transfer catalyst and undergoes electrophilic attack by an olefin. " Use of chiral amines has given rise to enantiomerically enriched epoxides (eq 42). 

Besides the secondary amine-catalyzed oxygenation reactions (see Sects. 2.3.1. and 3.2.5.) and phase-transfer catalyzed epoxidations (Chap. 6.) already mentioned, asymmetric epoxidation reactions using the method developed by Shi et al. (530) have found to be highly useful in complex total syntheses (531-535). The Shi epoxidation employs the fructose-derived ketone 629 as an easily available namral... 

Azizi, N., Saidi, M.R. 2007. Highly efficient ring opening reactions of epoxides with deactivated aromatic amines catalyzed by heteropoly acids in water. Tetrahedron 63(4) 888-891. 

Oxone and its derivatives have also been used with chiral iminium salts and amines to formenantiomerically enriched epoxides. The scope and enantioselectivity of epoxidation with chiral iminium salts with Oxone andPluPHSOs have made progress during recent years. Chiral iminium salts (7 and 8) have been particularly successful for various olefins (eqs 40 and 41). Amine-catalyzed epoxidation is a relatively new area, and the active species is thought to be an ammonium peroxymonosulfate salt which acts as a phase transfer catalyst and undergoes electrophilic attack by an olefin.Use of chiral amines has given rise to enantiomerically enriched epoxides (eq 42). 

Surendra, K., Krishnaveni, N.S. and Rao, K.R., The selective C-3 opening of aromatic 2,3-epoxy alco-hols/epoxides with aromatic amines catalyzed by /i-cyclodextrin in water, Synlett, 2005, 5806-5810. 

It has been found that tertiary amines are catalysts that not only affect the rate of the anhydride-epoxide reaction, but its course as well [82,83]. Dearborn and coworkers [84], for example, report that the highest crosslinking in amine-catalyzed anhydride-epoxide resin cures was obtained at a 1 1 anhydride expoxide ratio. This implies that the amine largely or wholly suppresses the undesirable side reaction of epoxide polymerization. This method of curing is potentially a powerful tool in polymer chemistry, since in its broadest sense it enables one to prepare a linear polyester containing at regular intervals along the chain various substituents available for further reactions. 

The ring-opening of epoxides with amines forming p-amino alcohols (Scheme 1.5) is a final example of an epoxide reaction catalyzed by DMCs [22]. Saikia et al. found that the Lewis acid Zn + sites in Zn-Fe(II)-DMC exhibit a good catalytic activity in these reactions at near-ambient, solvent-free conditions. The DMC catalysts display a high regioselectivity for the attack of primary amines at the most hindered position of the epoxide, as illustrated by reactions of aniline or butylamine with, for example, epichlorohydrin. The intrinsic activity of the catalyst rivals with and often exceeds that of many known catalysts for this reaction. 

Base-catalyzed anhydride-epoxide reactions have been found to have greater selectivity toward diester formation according to reaction (67). For potassium acetate-catalyzed reactions. Scheme 23 has been proposed. However, tertiary-amine-catalyzed reactions have been shown to proceed according to the Scheme 24. ... 

Zhang Z, Tang J, Wang X, Shi H. Chiral ketone- or chiral amine-catalyzed asymmetric epoxidation of cis-l-propenyl-phosphonic acid using hydrogen peroxide as oxidant. J. Mol. Catal. A Chem. 2008 285 68-71. 

The above studies [8-10] strongly indicate the participation of silanol groups as acid sites in the amine-catalyzed reactions. The synergistic catalysis of immobilized organic bases and silanol groups has been highlighted by the cyclic carbonate synthesis from carbon dioxide and epoxide. Acid-base dual activation mechanism of the cyclic carbonate synthesis is widely accepted. Sakakura and coworkers [11] reported silica-supported phosphonium salts as highly active catalysts for the cyclic carbonate synthesis. The results for propylene carbonate synthesis are summarized... 

Methylene chloride is one of the more stable of the chlorinated hydrocarbon solvents. Its initial thermal degradation temperature is 120°C in dry air (1). This temperature decreases as the moisture content increases. The reaction produces mainly HCl with trace amounts of phosgene. Decomposition under these conditions can be inhibited by the addition of small quantities (0.0001—1.0%) of phenoHc compounds, eg, phenol, hydroquinone, -cresol, resorcinol, thymol, and 1-naphthol (2). Stabilization may also be effected by the addition of small amounts of amines (3) or a mixture of nitromethane and 1,4-dioxane. The latter diminishes attack on aluminum and inhibits kon-catalyzed reactions of methylene chloride (4). The addition of small amounts of epoxides can also inhibit aluminum reactions catalyzed by iron (5). On prolonged contact with water, methylene chloride hydrolyzes very slowly, forming HCl as the primary product. On prolonged heating with water in a sealed vessel at 140—170°C, methylene chloride yields formaldehyde and hydrochloric acid as shown by the following equation (6). 

When the epoxide is to be used, a basic curing agent such as a tertiary amine, R3N, is added to cause the individual prepolymer chains to link together. This "cross-linking" of chains is simply a base-catalyzed epoxide... 

The reaction between epoxides and ammonia is a general and useful method for the preparation of P-hydroxyamines. " Ammonia gives largely the primary amine, but also some secondary and tertiary amines. The useful solvents, the ethanolamines, are prepared by this reaction. For another way of accomplishing this conversion, see 10-54. The reaction can be catalyzed with Yb(OTf)3 and in the presence of a-BINOL is l,l -bi-2-naphthol derivative gives amino alcohols with high asymmetric induction. A variation used Yb(OTf)3 at lOkbar or at ambient pressure. Lithium triflate can also be used. Primary and secondary amines give, respectively, secondary and tertiary amines, for example. 

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