The pyrrolidinone (IIIa) would then result from this intermediate by displacement of the nitrogen atom from C-5 by chloride ion. The mild conditions required for this bond cleavage strongly suggest a greatly weakened 1-5 bond of the pyrrolidine ring. This activation may be attributed to formation of the proposed intermediate. If the quaternary (VI) is, in fact, an intermediate then other nucleophiles should be capable of reaction at position 5 which ...
