Aniline, reaction with epoxides

Optically pure tri(hydroxyalkyl)amines 29 (R = Me, t-Bu, cyclohexyl or Ph) have been obtained from enantiomerically pure epoxides and methanolic ammonia63. Tetraphenylsti-bonium trifluoromethanesulphonate, SbPhzj1 C.f 3S03, catalyses the reaction of epoxides with amines, e.g. diethylamine or aniline, to yield 2-hydroxyalkylamines in quantitative yields (equation 25)64. 

The same differential behavior can be observed with amine nucleophiles. For example, calcium triflate promotes the aminolysis of propene oxide 84 with benzylamine to give 1-(A -benzyl)amino-2-propanol 85, the result of attack at the less substituted site <03T2435>, and which is also seen in the solventless reaction of epoxides with heterocyclic amines under the catalysis of ytterbium(III) triflate <03SC2989>. Conversely, zinc chloride directs the attack of aniline on styrene oxide 34 at the more substituted carbon center <03TL6026>. A ruthenium catalyst in the presence of tin chloride also results in an SNl-type substitution behavior with aniline derivatives (e.g., 88), but further provides for subsequent cyclization of the intermediate amino alcohol, thus representing an interesting synthesis of 2-substituted indoles (e.g., 89) <03TL2975>. 

Meio-epoxides undergo a ring-opening reaction with aromatic amines in the presence of a chiral metal-organic framework catalyst Zn2(L)(H20)2(A,A -dimethylacetamide)4 where L, [(S)-6,6 -dichloro-2,2 -diethoxy-1,T-binaphthyl-4,4 -bis(5-isophthalic acid)] is an organic linker between the zinc clusters Yields of the a-hydroxyamine ranging i from 70 to 95% with 62-89% ee were obtained using CM-stilbene epoxide and aniline. Lower yields and much lower ee values were found when different substituents were on the stilbene epoxide or the aniline. 

Electrochemical synthesis of cyclic carbonates from CO2 with epoxides, anilines, alcohols, and glycols was reported [53-60]. For example, Dunach et al. [54] conducted the reaction of epoxides with CO2 to the corresponding cyclic carbonates by an electrochemical method in the presence of nickel(II) complexes. In these methods, harmful organic solvents, supporting... 

It is worth mentioning that both the carboxylation of epoxides and anilines are acid-base reactions, which do not entail redox processes. Therefore a catalyst active in these reactions must provide acid-base functionality. In this perspective, positively charged gold could be the real player, although a co-catalytic or promotion effect of ze-rovalent gold could also be important. Therefore the catalysts for the oxidative carbonylation of aniline, supported on Merck Ion-exchanger IV, could be actually bifunctional. On one side, Au could catalyze the oxidation of CO with O2 to CO2, a reaction for which it is... 

Thioacetals eliminate to vinylsulfides in the presence of CuOTf (Scheme 46).192 Cu1 and Cu11 triflates are mild Lewis acids for Friedel-Crafts acylation and alkylation reactions. CuOTf effectively catalyzes the reaction of anisole with selenoesters.193,194 Copper(II) sulfate promotes epoxide ring opening reactions in the presence of pyridine,195 with retention of configuration being observed. Cu(OTf)2 is a catalyst for the ring opening of aziridine by aniline.196... 

Ring-opening with heteroatomic nucleophiles is certainly among the most thoroughly studied behavior of epoxides, and this reaction continues to be a versatile workhorse of synthetic utility. This is exemplified in the recent literature by the examples of the p-cyclodextrin-catalyzed aminolysis of simple epoxides by aniline derivatives (i.e., 53 - 54) <00SL339> and the synthesis of oxa-azacrown ethers through the treatment of Ws-epoxides 55 with diamines 56. Yields in the latter synthesis are sensitive to the size of the macrocycle and substitution on the bis-epoxide <00TL1019>. 

Scheme 31. Reaction for AlECR of trans epoxides with anilines as nucleophiles using the catalysts 67-69.

Table 9. Aminolytic kinetic resolution (AKR) of tra/is-stilbene epoxides using recyclable catalysts with aniline under different reaction conditions...

Kureshy, R. I. Singh, S. Khan, N. H. Abdi, S. H. R. Suresh, E. Jasra. R. V. (2006) Facile enantioselective ring-opening reaction of meso-epoxides with anilines using (5)-(-)-BlNOL-Ti complex as a catalyst., Ewr. J. Org. Chem., 1303-1309. 

A variety of rhodium complexes, including [Rh(CO)2Cl]2 and [Rh(COD)Cl]2 when used in combination with a variety of bisphosphine ligands, will catalyze the ring opening of vinyl epoxides in the presence of aniline nucleophiles [19, 20]. These reactions occur under very mild and neutral conditions (at room temperature or with mild heating) and are highly regio- and stereoselective. In all cases, nucleophilic attack occurs at the allylic epoxide carbon atom and proceeds with inversion of stereochemistry (Scheme 9.11). 

A double reduction was achieved under catalytic hydrogenation conditions to open the epoxide and reduce the nitro group to an amino group in 90% yield. The aniline thus afforded was reacted with diethylethoxymethylenemalonate to give 92. 92 was next cyclized to the 1,4-benzoxazine 93 via a Mitsunobu reaction in the absence of a Lewis acid, unlike Kim s approach (Kang et al., 1996). Completion of the tricycle core was ultimately achieved in PPE at 140-145°C to furnish the LVX core in 85% yield. The core was converted to LVX (1) in two precedented steps. 

Eastham and co-workers473 have determined the velocity of the-, reaction of ethylene oxide itself with diothylamine, aniline, and pyridine in aqueous solutions of pH 4-14. The reaction rate oould be expressed by a second-order equation, amine and epoxide terms cadi appearing to the first powor. Kate constants for the various aminos examined were, however, remarkably similar, showing little relation to their structure or basicity. Qualitatively similar trends had been reported previously by Smith and oo-workors.1587 1588... 

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