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2004
Multi-membered N-heterocycles
R 0690
4,5-Dihydro-3H-benzo[c]azepines from 1,7-Electrocyclization Reactions of
Compounds. — A novel method for the con49- 142 2-Aza-4,5-benzoheptatrienyllithium
struction of differently substituted dihydrobenzazepines (III)/(IV) is presented, involving the deprotonation of [2-(alkenyl)benzylidene]amines like (I) with LDA followed
by quenching with various electrophiles (II). An anionic 1,7-electrocyclization mechanism is proposed to proceed. The stereoselectivity of cyclization is shown to be sensitive to the C—C double bond geometry in the starting imines [cf. (I) vs. (V)]. Attempts to generate the corresponding nonacyclic analogues by cyclization of N-allyl
imines like (VI), however, are not successful. — (GERDES, K.; SAGAR, P.;
FROEHLICH, R.; WIBBELING, B.; WUERTHWEIN*, E.-U.; Eur. J. Org. Chem.
2004, 16, 3465-3476; Org.-Chem. Inst., Westfael. Wilhelms Univ., D-48149 Muenster,
Germany; Eng.) — Mischke
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