Synthesis of modified H4-BINOL ligands and their applications in the asymmetric addition of diethylzinc to aromatic aldehydes

Two new ligands (S,S)-3-(1,1′-bi-2-naphthol-3-yl)-5,6,7,8-tetrahydro-1,1′-bi-2-naphthol [(S,S)-1] and (S)-3-(morpholin-4-ylmethyl)-H4-BINOL [(S)-2] have been synthesized via Suzuki cross-coupling reaction and a Mannich-type reaction, respectively. In the presence of titanium tetraisopropoxide, 0.8 mol % of ligand (S,S)-1 catalyzed the asymmetric addition of diethylzinc to aromatic aldehydes in good yield and with high enantioselectivity.

Figure optionsDownload as PowerPoint slide

(S,S)-3-(1,1′-Bi-2-naphthol-3-yl)-5,6,7,8-tetrahydro-1,1′-bi-2-naphtholC40H30O4Ee = 100%[α]D25=-19.3 (c 1.01, CHCl3)Source of chirality: resolutionAbsolute configuration: (S,S)

(S)-3-(Morpholin-4-ylmethyl)-5,6,7,8-tetrahydro-1,1′-bi-2-naphtholC25H27NO3Ee = 100%[α]D25=-30.8 (c 1.06, CHCl3)Source of chirality: resolutionAbsolute configuration: (S)