Epoxidations primary-secondary diamine

The Zhao group recently disclosed an enantioselective epoxidation of a,P-unsaturated ketones promoted by primary-secondary diamine catalyst 13c the corresponding epoxides were obtained with excellent enantioselectivities (Scheme 3.19) [55],... 

Scheme 3.19 Primary-secondary diamine-catalyzed epoxidation.

Primary and secondary amines also react with epoxides (or in situ produced episulfides )r aziridines)to /J-hydroxyamines (or /J-mercaptoamines or 1,2-diamines). The Michael type iddition of amines to activated C—C double bonds is also a useful synthetic reaction. Rnally unines react readily with. carbonyl compounds to form imines and enamines and with carbo-tylic acid chlorides or esters to give amides which can be reduced to amines with LiAlH (p. Ilf.). All these reactions are often applied in synthesis to produce polycyclic alkaloids with itrogen bridgeheads (J.W. Huffman, 1967) G. Stork, 1963 S.S. Klioze, 1975). 

Benzyl methyl ether or allyl methyl ethers can be selectively metalated at the benzylic/allylic position by treatment with BuLi or sBuLi in THF at -40 °C to -80 C, and the resulting organolithium compounds react with primary and secondary alkyl halides, epoxides, aldehydes, or other electrophiles to yield the expected products [187, 252, 253]. With allyl ethers mixtures of a- and y-alkylated products can result [254], but transmetalation of the lithiated allyl ethers with indium yields y-metalated enol ethers, which are attacked by electrophiles at the a position (Scheme 5.29). Ethers with ft hydrogen usually undergo rapid elimination when treated with strong bases, and cannot be readily C-alkylated (last reaction, Scheme 5.29). Metalation of benzyl ethers at room temperature can also lead to metalation of the arene [255] (Section 5.3.11) or to Wittig rearrangement [256]. Epoxides have been lithiated and silylated by treatment with sBuLi at -90 °C in the presence of a diamine and a silyl chloride [257]. 

Diamines, a well-studied co-reactant with epoxy, are tetrafunctional where each amine hydrogen can react. The reactions of primary amine and secondary amine with epoxide are illustrated in equations 1 and 2, respectively. The heat of reaction Aifrxn for epoxy-amine is 106 kJ/mol ( 25.5 kcal/mol) for reaction with... 

Close examination of the individual spectra indicate that the cycloaliphatic diamine shows a strong preference for the primary amine reaction. With an excess of activator the primary amine reaction dominates resulting in a single exotherm. In the under-stoichiometric mix, excess epoxide groups remain after the majority of the primary amine has been consumed. The less reactive secondary amine apparently... 

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