Enantioselective ethylation of aldehydes using a regenerable polymer-supported N-picolylvalinol tridentate ligand

Exploiting thegem-Disubstitution Effect in FcPHOX and HetPHOX P,N Ligands: Synthesis and Applications in Pd-Catalyzed Intermolecular Heck Reactions

“…The synthesis of our HetPHOX ligand family began by the reaction of acid chloride 8 with gem -disubstituted amino alcohols 9 and 10 under biphasic reaction conditions to provide amides 11 and 12 in 77% and 83% yields, respectively (Scheme ). Heating the resulting gem- disubstituted tertiary alcohols in the presence of methanesulfonic acid (MsOH) was enough to promote dehydration and subsequent cyclization to form oxazolines 13 and 14 in 52% and 98% yields, respectively.…”

Recyclable Stereoselective Catalysts

“…Fig. 1.45 ) provided the respective phenylpropanols with excellent levels of enantioselectivities (up to 93% ee) and proved to be fully recyclable during fi ve cycles [205] . Hodge et al applied an N -methyl -diphenylprolinol grafted in polystyrene beads as catalyst for alkylzinc addition to benzaldehydes.…”

2-Amino-3-methyl-1,1-diphenyl-1-butanol

“…38 The polymer-supported catalyst can be recycled and has been used for the enantioselective ethylation of aldehydes, 85-93% ee, except 4-pyridinecarboxaldehyde (4% ee). 39 The bis-amide, obtained from 1 and oxalyl chloride, is a less selective ligand among the analogs in the Ti(IV)-catalyzed diethylzinc addition to benzaldehyde and aliphatic aldehydes. 40 1-Magnesiotetrahydroisoquinolyloxazoline derived from 1 adds diastereoselectively to benzaldehyde affording a mixture of two diastereomeric products, 80:20, which are difficult to separate.…”