Synthesen biologisch wichtiger Kohlenhydrate, 18. Die vic. cis ‐Oxyaminierung als Schlüsselreaktion für Aminozucker‐Synthesen: Methyl‐ N ‐acety‐4‐epi‐α‐garosaminid
1979; Wiley; Volume: 112; Issue: 5 Linguagem: Inglês
10.1002/cber.19791120535
ISSN0009-2940
Autores Tópico(s)Amino Acid Enzymes and Metabolism
ResumoMethyl-2-O-benzyl-3,4-didesoxy-α-Dglycero-pent-3-enopyranosid (11), das gut durch Corey-Winter-Olefinierung des 3,4-Thionocarbonats 10 zugänglich ist, reagiert mit Chloramin-T/kat. OsO4 zum 2:1-Gemisch des Methyl-2-O-benzyl-4-desoxy-4-tosyalmino- (12) und Methyl-2-O-benzyl-3-desoxy-3tosylamino-β-L-arabinosids (15). 15 wird mit Diazomethan zum N-Methyl-Derivat 16 umgesetzt, das mit kat. RuO2/KIO4 zu Methyl-2-O-benzyl-3-desoxy-3-(N-methyltosylamino)-β-L-threo-pentopyranos-4-ulosid (17)oxidiert wird. Grignard-Reaktion von 17 liefert stereospezifisch Methyl-2-O-benzyl-3-desoxy-4-C-N-methyl-3-(methyltosylamino)-α-D-xylopyranosid (19), aus dem die N-Tosylgruppe und der 2-O-Benzylrest mit Natrium in flüss. Ammoniak abgespalten werden. N-Acetylierung führt zu Methyl-3-desoxy-4-C-methyl-3-(N-methylacetylamino)-α-D-xylopyranosid (Methyl-N-acetyl-4-epi-α-garosaminid) (21). Syntheses of Biologically Important Carbohydrates, 18. The vic. cis-Oxyamination as the Key Reaction for Amino Sugar Syntheses: Methyl N-Acetyl-4-epi-α-garosaminde Methyl 2-O-benzyl-3,4-dideoxy-α-D-glycerol-pent-3-enopyranoside (11), easily available by Corey-Winter olefination of the 3,4-thionocarbonate 10, reacts with chloramines-T/cat. OsO4 to give the 2:1-mixture of methyl 2-O-benzyl-4-deoxy-4-tosylamino- (12) and methyl 2-O-benzyl-3-deoxy-3-tosylamino-β-L-arabinoside (15). With diazomethane 15 yields with N-methyl derivative 16 which is oxidized with cat. RuOO2/KIO4 TO FORM METHYL 2-O-BENZYL-3-DEOXY-3-(N-methyl-tosylamino)-β-L-threo-pentopyranos-4-uloside (17). Grignard reaction of 17 gives stereospecifically methyl 2-O-benzyl-3-deoxy-4-C-methyl-3-(N-methyltosyamino)-α-D-xylopyranoside (19) from which the N-tosyl group and the benzyl substituent at 2-O are split off with sodium in liquid ammonia. N-Acetylation yields methyl 3-deoxy-4-C-methyl-3-(N-methylacetylamino)-α-D-xylopyranoside (methyl N-acetyl-4-epi-α-garosaminide) (21).
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