Phosphites and diamidophosphites based on mono-ethers of BINOL: a comparison of enantioselectivity in asymmetric catalytic reactions

Application of Hydroxyporphyrins-based Phosphite-type Ligands to Asymmetric Pd-Catalyzed Allylic Substitution Reactions

“…These values suggest the anti-orientation of the pseudoequatorial exocyclic substituent at the phosphorus atom and the -(CH 2 ) 3 -part of the pyrrolidine fragment of the phosphabicyclic skeleton and, consequently, the synorientation of the phosphorus lone pair with respect to the C(8) atom (Figure 1). [13,18,[55][56][57][58][59] (S) In order to have an estimation of the steric bulk of ligands 4a-c and 5, we calculated their Tolman cone angles [60] by the reported method using semi-empirical quantum-mechanical AM1 techniques with full optimization of geometrical parameters. [61] The obtained results (Table 1) show that the steric parameters (q) of 4a-c and 5 vary within the interval of 121°-165°, peaking at diamidophosphite 4c.…”

Synthesis of binaphthyl based phosphine and phosphite ligands

“…The same authors reported the synthesis of phosphite ligands 28 (Fig. 12), containing dissymmetric BINOL fragments, 37,38 through the phosphorylation of differently monoprotected BINOL derivatives. These ligands have induced remarkable enantioselectivities in palladium-catalysed allylic substitution reactions.…”

NOBIN-based chiral phosphite-type ligands and their application in asymmetric catalysis

“…However, successful examples of Pdcatalyzed enantioselective allylic substitution with enamines are scarce, and this transformation 8 remains a challenge. 20,47,[61][62][63] Ligand 2 gave no conversion in this reaction, while ligands (R a ,R a )-3 and (R a ,S a )-3 led to the desired product as a mixture of anti-and syn-diastereomers 6a (up to 49% ee) and 6b (up to 93% ee), respectively, with low to good conversion and diastereomeric ratios. While the best diastereoselectivity and asymmetric induction were obtained with ligand (R a ,S a )-3 (Table 2, entry 6), its diastereoisomer (R a ,R a )-3 produced better conversion at room temperature (Table 2, entries 1, 2 and 5, 6).…”

“…See, for example, selected review articles [1][2][3][4][5][6] and literature reports regarding chiral phosphites, 7-13 phosphoramidites [14][15][16][17][18][19] and diamidophosphites. 20,21 The careful selection of a suitable chiral backbone has become crucial in the design of any modern stereoinducer for enantioselective catalysis. 22 Several naturally occuring building blocks, as well as binaphthyl and biphenyl derivatives, have been widely used in the development of phosphite-type chiral ligands.…”

“…Enamines can serve as convenient nucleophiles for Pd-catalyzed asymmetric allylic alkylations, avoiding the need to generate unstablilized ketone enolates using strong bases. However, successful examples of Pdcatalyzed enantioselective allylic substitution with enamines are scarce, and this transformation remains a challenge 20,47,[61][62][63]. Ligand 2 gave no conversion in this reaction, while ligands (R a ,R a )-3 and (R a ,S a )-3 led to the desired product as a mixture of anti-and syn-diastereomers 6a (up to…”