Azirine Weinreb amides: Preparation and use in the synthesis of 2-acylated aziridines and azirines.

Azirine Weinreb amides (N -methoxy- N -methyl-2 H -azirine-2-carboxamides) were synthesized in yields of 35–94 % by the reaction of N , O -dimethylhydroxylamine with 2 H -azirine-2-carbonyl chlorides, formed by the catalytic isomerization of 5-chloroisoxazoles. Red-Al reduction of azirine Weinreb amides affects only the azirine C N bond and leaves the C(O)NMeOMe group unaffected, forming stereoselectively 1-unprotected 3-substituted cis - N -methoxy- N -methylaziridine-2-carboxamides. The developed approach is a stereo-complementary addition to the previously proposed method for preparing unprotected trans - N -methoxy- N -methyl-3-phenylaziridine-2-carboxamide. The Weinreb amide group in the synthesized cis - N -methoxy- N -methylaziridine-2-carboxamides was used to prepare cis -2-acyl-3-arylaziridines by reaction with organometallic compounds. The reaction of organomagnesium compounds with azirine Weinreb amides allow the stereoselective preparation of 3-aryl-3-aryl/hetary/alkyl- N -methoxy- N -methylaziridine-2-carboxamides; which, in turn, were used to obtain the corresponding aziridinyl ketones. The reaction of azirine Weinreb amides with bulky substituents in the 3-position of azirine with organometallic compounds occurs only at the C(O)NMeOMe group with retention of the azirine C N bond with the formation of 2-acyl-2 H -azirines. [Display omitted] • Synthesis of azirine Weinreb amides. • Red-Al reduction of azirine Weinreb amides affects only the azirine C N bond. • Stereoselective approach to 1-unprotected cis - N -MeO- N -Me-aziridine-2-carboxamides. • Preparation of cis -2-acyl-3-arylaziridines and 2-acyl-2 H -azirines. • Stereoselective synthesis of 2-acyl-3-aryl-3-aryl/hetary/alkylaziridines. [ABSTRACT FROM AUTHOR]