No abstract

The 1,3-dipolar cycloaddition reaction of a non-stabilized azomethine ylide 4a, formed in situ from N-(methoxymethyl)-N-(trimethylsilylmethyl)benzylamine 5 and a catalytic amount of trifluoroacetic acid, with aromatic aldehydes 3 gives rise to N-benzyl-5-aryloxazolidines 1. Under these conditions, 4-hydroxybenzaldehyde 3p undergoes two-fold addition of azomethine ylide 4a to afford bis adduct 11.

A nonstabilized azomethine ylide reacts with a wide range of substituted isatoic anhydrides to afford novel 1,3-benzodiazepin-5-one derivatives, which are generally isolated in high yield. The transformations involve 1,3-dipolar cycloaddition reactions of the ylide with the anhydrides to give transient, and in a representative case spectroscopically observable, oxazolidine intermediates that undergo ring-opening-decarboxylation-ring-closing reaction cascades to yield the 1,3-benzodiazepin-5-one products.

The 1,3-dipolar cycloaddition of an unstabilized azomethine ylide, generated in situ by reaction of amine (I) with TFA, to (het)aromatic aldehydes (II) and (IV) provides an efficient access towards aryloxazolidines (III) and (V), respectively. A wide range of electron-withdrawing, electron-donating, acidic or basic substituents is tolerated. p-Hydroxybenzaldehyde (VI) undergoes double addition of azomethine ylide to give oxazolidine (VII). -(RYAN*, J. H.; SPICCIA, N.; WONG, L. S.-M.; HOLMES, A. B.; Aust.