Planar chiral [2.2]paracyclophane-based phosphine-phenol catalysts: application to the aza-Morita-Baylis-Hillman reaction of N-sulfonated imines with various vinyl ketones

Planar Chiral [2.2]Paracyclophane-Based Bisoxazoline Ligands: Design, Synthesis, and Use in Cu-Catalyzed Inter- and Intramolecular Asymmetric O–H Insertion Reactions

“…We have already reported that the single spacer in PCP-based phosphine-phenol catalysts (S p )-A ( Fig. 1, left) is crucial for achieving higher reactivity and enantioselectivity in the aza-Morita-Baylis-Hillman reactions of N-tosylaldimines and vinyl ketones 11,12) (Chart 1a). The phosphine catalysts (S p )-A can also be used in the highly enantioselective [3+2] annulations of allenoates and N-tosylaldimines 13) (Chart 1b).…”

Enantiopure planar chiral [2.2]paracyclophanes: Synthesis and applications in asymmetric organocatalysis

“…85 In addition to PhanePhos and its derivatives, planar chiral pCp-based bifunctional phosphine-phenol compounds have been prepared and used as catalysts in metal-free reactions (Scheme 23). [86][87][88][89] To access these compounds, 4-bromo-12-hydroxy[2.2] paracyclophane (S p )-47 is first isolated through a mono metalation of enantiomerically pure 4,12-dibromo[2.2]paracyclophane (S p )-21, followed by a reaction with trimethylborate, and oxidation of the resulting product with hydrogen peroxide and sodium hydroxide. The obtained key intermediate (S p )-47 is then engaged into a Suzuki-Miyaura coupling in the presence of phosphinylboronic esters.…”

“…87 Bifunctional phosphine-phenol pCp derivatives such as compound (S p )-49 have been employed to catalyze asymmetric aza-Morita-Baylis-Hillman reactions of aldimines with vinyl ketones (Scheme 24). 88,89 The same catalysts can also be used to promote enantioselective [3 + 2] annulations of unsubstituted allenic esters and N-tosylimines (Scheme 24). 86 In both transformations, bifunctional pCps provide better yields and enantioselectivities in comparison with PhanePhos or other planar chiral ligands.…”

Phosphine-Catalyzed Asymmetric Organic Reactions

“…In related studies, the groups of S ̌tepnicǩa and Kitagaki synthesized a series of ferrocene-based phosphines and planar chiral bifunctional phosphines, respectively, and evaluated their catalytic effects in the aza-MBH reactions of imines and vinyl ketones. 242,243 Wu and co-workers described an asymmetric MBH reaction of isatins with acrylates, catalyzed by cyclohexanediaminederived bifunctional phosphine catalysts. 244 In a follow-up study, the same group prepared a series of novel phosphine− squaramides and found catalyst P117 efficiently promoted the MBH reaction of isatin derivatives 432 and acrylates 433 (Scheme 131).…”