Functionalized analogues of Tröger's base: scope and limitations of a general synthetic procedure and facile, predictable method for the separation of enantiomers

Synthesis and NMR study of N-heterocyclic carbenes (NHC) precursors derived from Tröger’s Base

“…Firstly, Tröger's base and its analogues (1a-d) were synthesized according to the method described in the litterature 13,15,18 . Thereafter, we proceeded on the removal of methylene bridge by using the method of Mahon 16 . This lead to the corresponding diazocines (2a-d) that were used in the synthesis of perhalogenated and thiourea adducts.…”

An Easy and Efficient Synthesis of Bisindolylmethanes and Tetraindolylmethane Tröger's Base Catatlyzed by AgBF4

“…Initially, compound 7 was synthesized by the condensation of 4-bromoaniline with paraformaldehyde using TFA as solvent. 63 Lithium-halogen exchange of 7, followed by quenching by N-formyl piperidine, furnished dialdehyde 8. Further reaction of compound 8 with four equivalents of indole and 20 mol% of silver tetrafluoroborate under the aforementaioned conditions afforded 9 in good yield.…”

Thiourea derivatives of Tröger’s base: synthesis, enantioseparation and evaluation in organocatalysis of Michael addition to nitroolefins

“…Moreover, systematic separation of a library of Tröger's base analogues allowed us to build a predictive model which is based on simple mechanistic considerations. 14 In particular, we concluded that substituents on the aromatic rings in orthopositions to the N-atoms greatly decrease the enantioselectivity due to sterical constraints, unless they are efficient H-bond donors (e.g. NH 2 or OH groups).…”

“…Incorrect designation of the absolute configuration of C(3) results from the fact that the original version of this CSP had an eleven-carbon linker, but substitution of it by the three-carbon linker results in the inversion of Cahn-Ingold-Prelog priorities at C(3). 13 In the recent studies, 14,15 we demonstrated that CSP Whelk O1 is rather versatile for the separation of Tröger's base analogues, in which the chiral center itself (stereogenic N-atom) serves as an H-bond acceptor. Moreover, systematic separation of a library of Tröger's base analogues allowed us to build a predictive model which is based on simple mechanistic considerations.…”