Novel carbohydrate-derived pyridinecarboxylic organocatalysts for the enantioselective reduction of imines with trichlorosilane

A new type of carbohydrate-derived pyridinecarboxylic organocatalyst was prepared by fine-tuning a d-glucosamine backbone at the C-2 and C-3 positions. The carbohydrate-derived pyridinecarboxylic organocatalyst was used for the enantioselective reduction of imines with trichlorosilane. The reduction proceeded in high yield (up to 93%) and with moderate enantioselectivity (up to 75%).

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Benzyl-4,6-O-benzylidene-2-amino-2-deoxy-α-d-glucopyranosideC20H23NO5[α]D20=+59.7 (c 1.05, CHCl3)Source of chirality: N-acetyl-d-glucosamineAbsolute configuration: (1S,2R,3R,4S,5R)

Methyl-4,6-O-benzylidene-2-amino-2-deoxy-α-d-glucopyranosideC14H19NO5[α]D20=+103.1 (c 0.905, CHCl3)Source of chirality: N-acetyl-d-glucosamineAbsolute configuration: (1S,2R,3R,4S,5R)

Benzyl-4,6-O-benzylidene-2-acetylamino-2-deoxy-α-d-glucopyranosideC22H25NO6[α]D20=+56 (c 0.21, MeOH)Source of chirality: N-acetyl-d-glucosamineAbsolute configuration: (1S,2R,3R,4S,5R)

Methyl-4,6-O-benzylidene-2-acetylamino-2-deoxy-α-d-glucopyranosideC16H21NO6[α]D20=+90 (c 0.11, MeOH)Source of chirality: N-acetyl-d-glucosamineAbsolute configuration: (1S,2R,3R,4S,5R)

Benzyl-4,6-O-benzylidene-2-picolinamide-2-deoxy-α-d-glucopyranosideC26H26N2O6[α]D20=+40.0 (c 1.08, CHCl3)Source of chirality: N-acetyl-d-glucosamineAbsolute configuration: (1S,2R,3R,4S,5R)

Methyl-4,6-O-benzylidene-2-picolinamide-2-deoxy-α-d-glucopyranosideC20H22N2O6[α]D20=+24.9 (c 0.95, CHCl3)Source of chirality: N-acetyl-d-glucosamineAbsolute configuration: (1S,2R,3R,4S,5R)

Benzyl-4,6-O-benzylidene-3-O-(pyridinecarboxylic)-2-picolinamide-2-deoxy-α-d-glucopyranosideC32H29N3O7[α]D20=+47.2 (c 1.00, CHCl3)Source of chirality: N-acetyl-d-glucosamineAbsolute configuration: (1S,2R,3R,4S,5R)

Methyl-4,6-O-benzylidene-3-O-(pyridinecarboxylic)-2-picolinamide-2-deoxy-α-d-glucopyranosideC26H25N3O7[α]D20=+45.0 (c 1.1, CHCl3)Source of chirality: N-acetyl-d-glucosamineAbsolute configuration: (1S,2R,3R,4S,5R)

Benzyl-4,6-O-benzylidene-3-O-(pyridinecarboxylic)-2-acetylamino-2-deoxy-α-d-glucopyranosideC28H28N2O7[α]D20=+19.2 (c 0.97, CHCl3)Source of chirality: N-acetyl-d-glucosamineAbsolute configuration: (1S,2R,3R,4S,5R)