Epoxidation with nitrogen nucleophiles

Scheme 8E.28. Asymmetric alkylation of vinyl epoxide with nitrogen nucleophile.

Reaction of epoxides with nitrogen nucleophiles affords a variety of P-hydroxyamines and their equivalents. Comprehensive review articles have been published. In conjunction with the development of diastereoselective and enantioselective syntheses of epoxy alcohols, selective oxirane ring cleavage of 2,3-epoxy alcohols and carboxylates by nitrogen nucleophiles has become a versatile route to various amines and their equivalents. For details, the reader is referred to refs. lOSc and 103d. 

N-Nitrosopiperidine (carcinogen) with oxygen adds photolytically to alkenes to give A(-(2-nitro-alkyl)piperidines. Indirect methods of preparing amino alcohols from alkenes include the well-known trans opening of epoxides with nitrogen nucleophiles and a recent, complementary, cis opening of... 

In the presence of a palladium catalyst, allyl epoxides (113) react with nitrogen nucleophiles at the al-kenic carbon atom remote from the oxirane ring to give 1,4-adducts (114)." In the absence of a palladium catalyst, azide ion attacks the oxirane ring affording 1,2-adducts (115 Scheme 52 and Table 2)." Vinyl epoxide (116) gave 1,2- and 1,4-azido alcohol in a ratio of 1 1.5 irrespective of the reaction system. " Intramolecular cyclization of vinyl epoxide (117) in the presence of a palladium catalyst afforded isoquinuclidine (118 Scheme 52). ... 

Reactions with Nitrogen Nucleophiles. Treatment of an epoxide with one of the diethylaluminium amides [153 = Et, CHjPh, or CH2CH=CH2 ... 

The first section of this chapter describes the preparation and several synthetic applications of a-fluoroalkyl P-sulfmyl enamines and imines the second deals with the chemistry of di- and trifluoropyruvaldehyde A, 5-ketals, stereochemically stable synthetic equivalents of P-di and P-trifluoro a-amino aldehydes, which can be prepared from the corresponding p-sulfinyl enamines the third overviews the preparation of chiral sulfinimines of trifluoropyruvate and their use to prepare a library of a-trifluoromethyl (Tfm) a-amino acids the fourth section is mainly dedicated to the asymmetric synthesis of monofluorinated amino compounds, using a miscellany of methods such as MifstmobuAike azidation of P-hydroxy sulfoxides, ring opening of fluoroalkyl epoxides with nitrogen-centered nucleophiles and 1,3-dipolar cycloadditions with chiral fluorinated dipolarophiles. 

A rather complex microwave-assisted ring-opening of chiral difluorinated epoxy-cyclooctenones has been studied by Percy and coworkers (Scheme 6.131) [265]. The epoxide resisted conventional hydrolysis, but reacted smoothly in basic aqueous media (ammonia or N-methylimidazole) under microwave irradiation at 100 °C for 10 min to afford unique hemiacetals and hemiaminals in good yields. Other nitrogen nucleophiles, such as sodium azide or imidazole, failed to trigger the reaction. The reaction with sodium hydroxide led to much poorer conversion of the starting material. 

The strained rings of epoxides and oxetanes are susceptible to nucleophilic attack. In this section we discuss the reactions of these oxygen heterocycles with nitrogen oxides and other... 

A chiral, nonracemic oxirane, (3 )-2-[(R)-fluoro(phenyl)methyl]oxirane, can react with (chiral) amines under the influence of lithium perchlorate using either heat or microwave irradiation. This reaction sequence provides a material from which the ee of chiral a-branched amines can be determined <2005OL3829>. Guanidines serve as a useful nitrogen nucleophile for the direct conversion of epoxides to aziridines <2004JOC8504>. 

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