Chiral 2 + 3 Keto-Enamine Pseudocyclophanes Derived from 1,3,5-Triformylphloroglucinol

The reactions of
1,3,5-triformyl­phloro­glucinol with
(1R,2R)-1,2-diamino­cyclo­hexane,
(1R,2R)-1,2-diphenyl­ethylene­diamine,
or (R)-2,2′-diamino-1,1′-binaphthyl
result in the formation of enantiopure [2 + 3] keto-enamine condensation
products, in contrast to analogous reactions of 1,3,5-triformylbenzene,
where [4 + 6] Schiff base cages are formed. The X-ray crystal structure
of the diamino­cyclohexane 2 + 3 derivative as well as modeled
structures of other compounds of this type show cyclophane-like molecules
with close contact between the phloroglucinol rings. Density Functional
Theory (DFT) calculations confirm that there is a sizable π–π
interaction between these rings influencing the conformation of these
molecules.