Sodium borohydride → HCID 20326287, compound
Reaction equation
[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+]>>[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]Participants
3
Procedure
To a solution of 10 g of crystalline antibiotic X-537A in 500 ml of absolute ethanaol 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 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-5-hydroxy-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).