Debenzylated dihydropyrrole

Direct debenzylation of pyrroles 137 using Pd-catalyzed hydrogenation proved unsuccessful, but it was shown that if NH-pyrrole is required, debenzylation was easier to achieve on the dihydropyrrole intermediate 139, using 1-chloroethyl chloroformate. The debenzylated dihydropyrrole 140 can then be aromatized in the usual manner by treatment with DDQ to form 3-SF5-4-(3-thienyl)-AM-pyrrole (141) (Scheme 41). 

Scheme 11.33. Aminocyclopropanation of N-protected 2,5-dihydropyrroles 126 and debenzylation of the exo-6-amino-3-azabicyclo[3.1. OJhexane 129 [105b, 113].

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