Die Struktur des Adduktes aus 3‐Dimethylamino‐2,2‐dimethyl‐2 H ‐azirin und 3‐Methyl‐2,4‐diphenyl‐1,3‐oxazolium‐5‐olat. Vorläufige Mitteilung

Structure of the adduct from 3‐dimethylamino‐2,2‐dimethyl‐2 H ‐azirine and 3‐methyl‐2,4‐diphenyl‐1,3‐oxazolium‐5‐olate 3‐Dimethylamino‐2,2‐dimethyl‐2 H ‐azirine ( 1 ) reacts with 3‐methyl‐2,4‐diphenyl‐1,3‐oxazolium‐5‐olate ( 5a ) to give a 1:1 adduct ( 7 ) in a 88% yield. Its crystal structure has been determined by X‐ray analysis (direct methods) and refined with 1056 structure amplitudes to R = 0,032. The crystal system is monoclinic, space group P 2 1 / c , with unit cell dimensions a = 10.663, b = 9,828, c = 18,592 Å, and β = 90,63°. It is obvious that 4‐dimethylamino‐5,5‐dimethyl‐2‐[α‐( N ‐methyl‐benzamido)benzyliden]‐Δ 3 ‐1,3‐oxazoline ( 7 ) arises from an addition of 1 to the valence‐polaromeric ketene form 5b of the mesoionic oxazolone 5a (Scheme 3) .