Asymmetric Mannich Reaction And Alkynylation Of Seven-membered Imines Dibenzo-1,4-oxazepines

Asymmetric addition of cyclic imines offers a convenient and straightforward access to optically active N-heterocycles with an adjacent stereocentre. Dibenzo-1,4-oxazepine derivatives play an important role in synthetic organic chemistry and pharmaceutical science, and their structures are seven-membered cyclic imines with endocyclic reactive C,N-double bonds and two phenyl rings. In the dissertation, asymmetric Mannich reaction and alkynylation of seven-membered cyclic imines dibenzo-1,4-oxazepines were studied in presence of chiral catalysts.1. Organocatalysed asymmetric direct Mannich reactionThe Mannich reaction proves to be one of the most versatile techniques for the formation of carbon–carbon bonds. An enantioselective direct Mannich reaction of different acetophenone derivatives with various substituted seven-membered cyclic imines using(S)-azetidine-2-carboxylic acid via enamine catalysis was studied. The carbonyl of Mannich products was also transformed to other functional groups.2. Asymmetric alkynylation of seven-membered cyclic imines by combining chiral phosphoric acids and Ag(I) catalysts.Chiral propargylamines are important synthetic intermediates for the construction of biologically active nitrogen-containing compounds and natural products. Therefore, the asymmetric synthesis of them is very attractive. Alkynylation of seven-membered cyclic imine dibenzo[b,f][1,4]oxazepines could be catalyzed by combined chiral phosphoric acid and Ag(I) catalysts with up to 99% ee. When H2/Lindlar catalyst or LiAlH4 was used, the alkynyl of the adducts could be reduced to(Z)- or(E)- alkenes.