Halogeno-substituted ring systems

Dibenzo[h./]oxepins and dibenzo[hJ]thiepins have important medicinal uses and can be prepared by irradiation of halogeno-substituted acetophones in liquid ammonia in the presence of bases (Nagaoka). A novel 1,9-hydrogen atom abstraction occurs on irradiation of 47 to give ultimately the keto ether 48 (Mizuno et al.) and previously unknown polycyclic ring systems such as 49,... 

Summary In contrast to organyl-substituted cyclodisilazanes, only a few halogeno substituted Si-N rings are known. Normally LiF elimination from lithium fluorosilylamides leads to the formation of four-membered Si-N rings. Using THF as solvent, a THF cleavage occurs and by-products are observed. Lithiated aminotrichlorosilanes react with THF under formation of new fourteen-membered heterocycles. An unknown Hit-electron system was isolated after thermal treatment of lithiated 2,6-diisopropylphenylfluorosilylamine. 

B.ii. Halogeno- or TViflyloxy-Substituted Five-Membered Ring Systems B.ii,a. Arylation... 

D.ii. Halogeno- or Triflyloxy-Substituted Six-Membered Ring Systems... 

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