Sodium borohydride → HCID 20326287, Verbindung
Reaktionsgleichung
[CH3:1][CH2:2][C@@H:3]([C:22]([C@H:24]([C@@H:26]([OH:42])[C@@H:27]([CH2:29][CH2:30][C:31]1[CH:36]=[CH:35][C:34]([CH3:37])=[C:33]([OH:38])[C:32]=1[C:39]([OH:41])=[O:40])[CH3:28])[CH3:25])=[O:23])[C@H:4]1[O:8][C@@:7]([C@@H:11]2[O:16][C@@H:15]([CH3:17])[C@@:14]([OH:20])([CH2:18][CH3:19])[CH2:13][CH2:12]2)([CH2:9][CH3:10])[CH2:6][C@@H:5]1[CH3:21].[BH4-].[Na+]>C(O)C>[CH3:37][C:34]1[CH:35]=[CH:36][C:31]([CH2:30][CH2:29][CH:27]([CH3:28])[CH:26]([OH:42])[CH:24]([CH3:25])[CH:22]([OH:23])[CH:3]([CH2:2][CH3:1])[CH:4]2[CH:5]([CH3:21])[CH2:6][C:7]([CH2:9][CH3:10])([CH:11]3[CH2:12][CH2:13][C:14]([CH2:18][CH3:19])([OH:20])[CH:15]([CH3:17])[O:16]3)[O:8]2)=[C:32]([C:39]([OH:41])=[O:40])[C:33]=1[OH:38]Komponenten
4
Edukt 2
Produkt 1
Reagenzien, Katalysatoren, Lösungsmittel 1
Versuchsvorschrift
To a solution of 10 g of crystalline antibiotic X-537A in 500 ml of absolute ethanol was added 1.36 g of NaBH4. The reaction was followed by assaying with thin layer chromatography (silica gel - CHCl3 /acetone 8:2) and the reaction was continued overnight after adding an additional 1.0 g. of NaBH4. The following morning the solvent was removed under reduced pressure and the heavy oil diluted with methylene chloride, washed with dilute HCl, dried (Na2SO4), and concentrated to a solid foam. The slightly pink solid was chromatographed on a 500 g silica gel column eluting with 2 l. hexane-methylene chloride (1:1), 2 l. methylene chloride 2 l. methylene chloride ether (1:1), The 250 ml fractions were assayed by TLC and fractions 13-17 pooled, concentrated to a yellow solid and rechromatographed on a 150 g florisil column eluting with a gradient from hexane to acetone. The fractions containing 3-methyl-6-{4,6-dihydroxy-3,5-dimethyl-7-ethyl-7-]5-ethyl-3-methyl-5-(5-ethyl-5-hydroxy-6-methyl-2-tetrahydropyranyl 2-tetrahydrofuryl]heptyl}salicylic acid were pooled and concentrated to a small volume from which pure 3-methyl-6-{4,6-dihydroxy-3,5-dimethyl-7-ethyl-7 -[5-ethyl-3-methyl-5-(5-ethyl-6-methyl-2-tetrahydropyranyl) 2-tetrahydrofuryl]heptyl}salicylic acid crystals were recovered, m.p. 151°-153°. From the mother liquor, additional material was crystallized, [α]D25 + 0.83 (C=.60%, CH3OH).