A-Lactams, synthesis

In 1050 Sheehan and Bose reported the formation of an asetidi-none by intramolecular alkylation of an -haloa( ]aminomalonk ester (Eq. 40). ThiB was the first example of a -lactam synthesis in which the amide bond was first established, and it is the only case 3 which any azetidine ring has been formed by cydisation of a hetero-ehain at a C—C bond. 

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