Covalently linked phosphoric acids – Applications in self-assembly and organocatalysis

Firstly, we have reported the successful synthesis of a novel bis-binaphthyl-guanidine. To this end, a new synthetic route was established, synthesizing the bis-guanidine (S,S)-28 in 12 steps starting from BINOL. Furthermore, guanidinium–phosphate pairing was successfully employed for the formation of a complementary double-helical structure. Here, the homochiral complex ((S,S)-28+ (S,S)-29 gives an intertwined double-helical structure with left-handed helicity. In contrast, the heterochiral paired complex (S,S)-28+(R,R)‑29 forms a non-helical dimeric structure. Secondly, a library of novel catalysts was synthesized. We were able to successfully apply this new generation of phosphoric acids for the transfer hydrogenation of 2-substituted quinoline derivatives. In this context, the flexibly linked bisphosphoric acids (R,R)-8 and(R,R)-11 provided excellent stereoselectivities (90-96% ee) for all substrates investigated (see Figure 76). In Addition, chiral anionic phase transfer catalysis was also investigated. The dearomative fluorination reaction of 1‑aryl-2-naphtols with the rigidly linked catalyst (R,R)-4a gave moderate to good stereoselectivities (50-78% ee)(see Figure 77).


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