ChemInform Abstract: Lewis Acid‐Catalysed Reactions of 2,2,2‐Trichloroethyl 6‐Diazopenicillanate and Imines: Rearrangements of Spiro‐6‐aziridine‐ and Spiro‐6‐oxiranepenicillanates. X‐Ray Crystal Structures of (3S,6′S)‐2,2,2‐Trichloroethyl 3‐(4‐Nitrophenyl)‐1‐phenylspiro(aziridine‐2,6′‐penicillanate) and (3S,7aR)‐2,2,2‐Trichloroethyl 2,3,5,7a‐Tetrahydro‐7‐methoxy‐2,2‐dimethyl‐6‐(4‐nitrophenyl)‐5‐oxopyrrolo(2,1‐b)thiazole‐3‐carboxylate.

Abstract In the presence of BF3, the penicillanate (I) and the imines (II) react to form the aziridines (III) and (IV), the thiazolo‐pyrimidinones (V) and the pyrrolothiazole (VId); rearrangement of (IIIa)‐(IIIc) with BF3 affords the pyrrolothiazoles (VIa)‐(VIc).