Zur Aktivierung partiell silylierter Kohlenhydrate mittels Triphenylphosphan/Azodicarbonsäureester

摘要: On the Activation of Partially Silylated Carbohydrates Using Triphenylphosphane/Diethylazodicarboxylate Reaction methyl α-D-glucopyranoside (1) with two equivalents t-butyldimethylchlorosilane yields 2,6-bis[O-(t-butyldimethylsilyl)]-α-D-glucopyranoside (1a) and 3,6-bis[O(t-butyldimethylsilyl)]-α-D-glucopyranoside (1b) in a ratio 4:1. The anomeric β-pyranoside 2 affords 2,6-bis[O(t-butyldimethylsilyl)]-β-D-glucopyranoside (2a) 3,6-bis[O(t-butyldimethylsilyl)]-β-D-glucopyranoside (2b) nearly equal amounts. 2b is isomerized to 4,6-bis[O(t-butyldimethylsilyl)]-β;-D-glucopyranoside (2c) (83%) 2a (10%) triphenylphosphane/diethylazodicarboxylate. Structures were assigned by NMR.-analysis CD.-analysis corresponding benzoates 1c, 1d 2d acetates 2e 2f. 1a transformed into 4-azido-2, 6-bis[O(t-butyldimethylsilyl)]-4-deoxy-α-D-galactopyranoside (3) triphenylphosphane/diethylazodicarboxylate/HN3. 2c yield 3-azido-allosides 5 7 respectively under similar conditions. activation triphenylphosphane/diethylazodicarboxylate high enough introduce also p-nitrobenzoate groups inversion configuration at reaction center. By this way 1a give 2, 6-bis[O(t-butyldimethylsilyl)]-4-O-p-nitrobenzoyl-α-D-galactopyranoside (4) 6-bis[O-(t-butyldimethylsilyl)]-3-O−ptrobenzoyl-β-D-allopyranoside (6) respectively. For elucidation structures acetate derivatives 3a-7a prepared.