Hydrazine reaction with epoxide

Other methods of generating a-aminoketones in situ are common, if somewhat less general than the methods already described. 2-Nitrovinylpyrrolidine, which is readily available, yields 2,3-bis(3-aminopropyl)pyrazine on reduction and this almost certainly involves ring opening of the intermediate enamine to an a-aminoketone which then dimerizes under the reaction conditions (Scheme 59) (78TL2217). Nitroethylene derivatives have also served as a-aminoketone precursors via ammonolysis of the derived epoxides at elevated temperatures (Scheme 60) (76S53). Condensation of 1,1-disubstituted hydrazine derivatives with a-nitro-/3-ethoxyethylene derivatives has been used in the synthesis of l,4-dialkylamino-l,4-dihydropyrazines (Scheme 61) (77S136). 

The azidohydrins obtained by azide ion opening of epoxides, except for those possessing a tertiary hydroxy group, can be readily converted to azido mesylates on treatment with pyridine/methanesulfonyl chloride. Reduction and subsequent aziridine formation results upon reaction with hydrazine/ Raney nickel, lithium aluminum hydride, or sodium borohydride/cobalt(II)... 

The successful synthesis of 2-thienyl and substituted 2- and 3-thienyl-acetylenes in yields as high as 60-80% opened a wide variety of synthetic applications. Various addition reactions with carbonyl compounds or epoxides could be carried out with ease. Aliphatic as well as aromatic amine addition reactions, or condensation reactions with hydrazine or hydroxylamine could be easily performed. 

Five-membered heterocycles have been used as substitutes for the y-lactone ring of cardenolides. Thus, the 17 -(5 -isoxazolyl)- and 17)8-(3 -pyrazolyl)-cardenolides (526) and (527) have been prepared from 20-ethoxy-21-formyl-3 -acetoxy-17)8-pregna-5,14,20-triene (528) by reaction with hydroxylamine and hydrazine hydrate, respectively. The isomeric 14a,15a- and 14) ,15/S-epoxides (529) and (530) in both series were then obtained by peracid treatment or alkaline cyclization of the respective 14,15-bromohydrin. 

Reactions of epoxides with amines, azides, hydrazines, etc., formation of N-heterocycles by epoxide ring opening 04ZOR11. 

Verbanone and its derivatives are normally made by oxidation of a-pinene [usually (+ )-116] when Takayanagi and Nishino required (— )-trans-verbanone (822), they used a synthetic procedure starting from (+ )-apoverbenone [(+ )-823] accessible from the ( —)-p-pinene series. The Wharton reaction (hydrazine hydrate) with the (trons)-epoxide of 823 yields 824, which can be oxidized to (— )-apoverbenone [( —)-823], from which 822 was obtained by reaction with lithium dimethyl cuprate. [This work was actually to prepare verbanyl acetates, the (l/ ,2/ ,5/ )-series of which notably ( + )-825 is active as pheromone mimics in the cockroach Periplaneta americana, while the (15,2S,5S)-series from 822 are inactive. 

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