Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Racemic and enantiomerically pure methyl N-(tert-butyl)-N-benzyl- and N-1-(phenylethyl)aziridinecarboxylates are prepared by known methods and converted to phenyl thioesters (1, 2, 15, 16; Schemes 2 and 3). These are deprotonated with lithium diisopropylamide (LDA) and BuLi (for removal of diisopropylamine) in THF at dry-ice temperature. The resulting lithiated species are surprisingly stable and are deuterated, alkylated (CH3, C2H5, allyl, benzyl), and added to aldehydes and nitroolefins in good yields (50-80 %, 18 examples; Schemes 1 and 4-6). The configurational stability of the lithiated species is studied, and conclusions about their structures are drawn. Thus, a C(α)-lithiated ester (see L, Scheme 9) or an O-lithiated ‘enolate’ (see M) with pyramidalized C(β)-atom is proposed for the species from levorotatory S-phenyl N-benzylaziridinecarbothioate which does not undergo racemization after 1 h at -60° (THF solution).
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