On the scope of diastereoselective aziridination of various chiral auxiliaries derived N- and O-enones with N-aminophthalimide in the presence of lead tetraacetate

The treatment of a range of N- and O-enones derived from various camphor-based chiral auxiliaries A–D with N-aminophthalimide in the presence of lead tetraacetate is described. In general, N-phthalimidoaziridines were obtained with high diastereoselectivities (up to 98% de) and chemical yields (up to 95%) when 10,10-diphenyl-2,10-camphanediol A derived O-enones with a range of substituents were used under the same reaction conditions. Excellent stereoselectivity was obtained when the N-tosyl camphorpyrazolidinone E derived acrylate was used. The absolute configuration of the new stereogenic center(s) of the major diastereomer was established by X-ray crystallographic analysis. Chiral auxiliary cleavage was achieved under mild reaction conditions. A model to explain the stereochemical induction is also proposed.

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1-(1,3-Dioxo-1,3-dihydro-isoindol-2-yl)-aziridine-(2R)-carboxylic acid methyl esterC12H10N2O4[α]D = +109.5 (c 1, CHCl3)Absolute configuration: (2R)