The synthesis of dendritic BINOL ligands and their applications in the asymmetric addition of diethylzinc to benzaldehyde

The synthesis of Fréchet-type dendritic BINOL ligands is described. These dendritic BINOL ligands were found to be effective in the enantioselective addition of diethylzinc to benzaldehyde both in the presence and absence of Ti(O-i-Pr)4. In the latter case, the novel dendritic chiral BINOL ligands showed slightly higher enantioselectivities than their monomeric analogue.

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(3,5-Bis(((R)-2,2′-bis(methoxymethoxy)-1,1′-binaphthyl-3-yl)methoxy)phenyl)methanolC57H52O11Ee = 100%[α]D20=+103 (c 1.0, CH2Cl2)Source of chirality: (R)-BINOLAbsolute configuration: (R)

(1R,1′R)-3,3′-(5-(Phenoxymethyl)-1,3-phenylene)bis(oxy)bis(methylene)bis(2,2′-bis(methoxymethoxy)-1,1′-binaphthyl)C63H56O11Ee = 100%[α]D20=+90 (c 1.0, CH2Cl2)Source of chirality: (R)-BINOLAbsolute configuration: (1R,1′R)

(1R,1′R)-3,3′-(5-(Phenoxymethyl)-1,3-phenylene)bis(oxy)bis(methylene)di-1,1′-binaphthyl-2,2′-diolC55H40O7Ee = 100%[α]D20=+46 (c 1.0, CH2Cl2)Source of chirality: (R)-BINOLAbsolute configuration: (1R,1′R)

(3,5-Bis(3,5-bis(((R)-2,2′-bis(methoxymethoxy)-1,1′-binaphthyl-3-yl)methoxy)benzyloxy)phenyl)methanolC121H108O23Ee = 100%[α]D20=+88 (c 1.0, CH2Cl2)Source of chirality: (R)-BINOLAbsolute configuration: (R)

(1R,1′R,1″R,1‴R)-3,3′,3″,3‴-(5,5′-(5-(Phenoxymethyl)-1,3-phenylene)bis(oxy)bis(methylene)bis(benzene-5,3,1-triyl))tetrakis(oxy)tetrakis(methylene)tetrakis(2,2′-bis(methoxymethoxy)-1,1′-binaphthyl)C127H112O23Ee = 100%[α]D20=+76 (c 1.0, CH2Cl2)Source of chirality: (R)-BINOLAbsolute configuration: (1R,1′R,1″R,1‴R)

(1R,1′R,1″R,1‴R)-3,3′,3″,3‴-(5,5′-(5-(Phenoxymethyl)-1,3-phenylene)bis(oxy)bis(methylene)bis(benzene-5,3,1-triyl))tetrakis(oxy)tetrakis(methylene)tetra-1,1′-binaphthyl-2,2′-diolC111H80O15Ee = 100%[α]D20=+49 (c 1.0, CH2Cl2)Source of chirality: (R)-BINOLAbsolute configuration: (1R,1′R,1″R,1‴R)

(R)-2,2′-Bis(methoxymethoxy)-3-(phenoxymethyl)-1,1′-binaphthylC31H28O5Ee = 100%[α]D20=+28 (c 1.0, CH2Cl2)Source of chirality: (R)-BINOLAbsolute configuration: (R)

(R)-3-(Phenoxymethyl)-1,1′-binaphthyl-2,2′-diolC27H20O3Ee = 100%[α]D20=+53 (c 1.0, CH2Cl2)Source of chirality: (R)-BINOLAbsolute configuration: (R)