The reaction of 4,4,4-trifluoro-3-oxobutanoates with the corresponding electron-rich amino heterocycles was investigated. A simple and flexible general procedure for the regiospecific annulation of the trifluoromethylpyridine ring to electron-rich amino heterocycles was proposed. A set of CF 3 -containing fused pyridines in almost quantitative yield was obtained.

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The Castagnoli-Cushman reaction with benzo[d]oxepine-2,4(1H,5H)-dione as an anhydride component allowed for preparation of 2,3-disubstituted 4-oxo-2,3,4,5-tetrahydro-1H-benzo[d]azepine-1-carboxylic acids in 21-75% yields and with good trans diastereoselectivity. The method worked with imines generated from aromatic or α-branched aliphatic aldehydes and is amenable for both parallel synthesis and scale-up. The procedure for epimerization of the resulting trans-disubstituted tetrahydrobenzo[d]azepines to their cis isomers was also developed.