Branched-chain sugar nucleosides. IV. 9-(3-Deoxy-3-C-"hydroxymethyl"-β(and α)-D-allofuranosyl and ribofuranosyl)adenine

1969 ◽  
Vol 47 (23) ◽  
pp. 4477-4481 ◽  
Author(s):  
Alex Rosenthal ◽  
Matej Sprinzl
Keyword(s):  
Hydrogen Peroxide ◽  
Sodium Methoxide ◽  
Titanium Tetrachloride ◽  
Total Yield ◽  
Borohydride Reduction ◽  
Peroxide Oxidation ◽  
Alkaline Hydrogen Peroxide ◽  
Sodium Metaperiodate ◽  
Sodium Borohydride Reduction ◽  
Branched Chain

Hydroboration followed by alkaline hydrogen peroxide oxidation of 1,2:5,6-di-O-isopropylidene-3-C-methylene-α-D-ribo-hexofuranose (2) yielded 3-deoxy-3-C-"hydroxymethyl"-1,2:5,6-di-O-isopropylidene-α-D-allofuranose (3) and partially hydrolyzed 3 in a total yield of 88%. Compound 3 was hydrolyzed selectively to the 1,2-monoisopropylidene derivative 5, which was converted via benzoylation followed by acetolysis into the 1,2-diacetate 7. Condensation of the latter compound with chloromercuri-N-benzoyladenine in the presence of titanium tetrachloride, followed by deblocking with methanolic sodium methoxide, yielded 9-(3-deoxy-3-C-"hydroxymethyl"-β(and α)-D-allofuranosyl)adenine in yields of 44 and 4% respectively, based on 7. The over-all yield of 10 based on 3 is 20%. Sodium metaperiodate oxidation of 10, followed by sodium borohydride reduction of the aldehydo-derivative, afforded 9-(3-deoxy-3-C-"hydroxymethyl"-β-D-ribofuranosyl)adenine (11) in 81% yield.Direct acetolysis of 3, followed by conversion of the mixture of peracetates into a mixture of glycosyl chlorides, and finally condensation of the latter with 8 gave the blocked crystalline β-D-nucleoside 9 in an over-all yield of about 9%, based on 3. Subsequent unblocking of 9 gave a nucleoside having the same physical constants as 10.

Branched-chain sugar nucleosides. III. 9-(3-Deoxy-3-C-methyl-β-D-allofuranosyl and ribofuranosyl)adenine

1969 ◽  
Vol 47 (21) ◽  
pp. 3941-3946 ◽  
Author(s):  
Alex Rosenthal ◽  
Matej Sprinzl
Keyword(s):  
Sodium Borohydride ◽  
Titanium Tetrachloride ◽  
Borohydride Reduction ◽  
Reaction Conditions ◽  
Sodium Metaperiodate ◽  
Sodium Borohydride Reduction ◽  
Branched Chain ◽  
Wittig Reagent

Condensation of triphenylphosphinemethylene (Wittig reagent) with 5-O-benzyl-1,2-O-isopropyl-idene-α-D-erythro-pentafuranos-3-ulose and with 1,2:5,6-di-O-isopropylidene-α-D-ribo-hexofuranos-3-ulose (1) afforded 5-O-benzyl-1,2-O-isopropylidene-3-deoxy-3-C-methylene-α-D-ribofuranose in 36% yield and 1,2:5,6-di-O-isopropylidene-3-C-methylene-α-D-ribo-hexofuranose (2) in 55% yield, respectively. A detailed study of the affect of reaction conditions on the yield of the unsaturated sugar is described. Hydrogenation of 2 proceeded stereoselectively to yield 4 which was hydrolyzed selectively to the 1,2-O-monoisopropylidene derivative 5. Benzoylation of the latter gave 6 which was converted by acetolysis to the 1,2-diacetate 7. Condensation of this compound with 6-benzamidochloromercuripurine in the presence of titanium tetrachloride followed by deblocking with methanolic sodium meth-oxide, yielded 9-(3-deoxy-3-C-methyl-β-D-allofuranosyl)adenine (10) in 48% yield based on 7. Sodium metaperiodate oxidation of 10, followed by sodium borohydride reduction of the aldehydo derivative, afforded 9-(3-deoxy-3-C-methyl-β-D-ribofuranosyl)adenine (11) in 85% yield.

Steroidal α,β-epoxyketones. IV. Synthesis of the isomeric 6β-Bromo-4,5-epoxycholestan-3-ones

1965 ◽  
Vol 18 (7) ◽  
pp. 1049 ◽  
Author(s):  
DJ Collins ◽  
JJ Hobbs
Keyword(s):  
Hydrogen Peroxide ◽  
Acetic Acid ◽  
Sodium Borohydride ◽  
Hydrogen Bromide ◽  
High Yield ◽  
Borohydride Reduction ◽  
Compound Xiii ◽  
Alkaline Hydrogen Peroxide ◽  
Sodium Borohydride Reduction

6β-Bromocholest-4-en-3-one (I) was converted to 6β-bromo-4α,5-epoxy-5α-cholestan-3-one (II) with alkaline hydrogen peroxide. 5,6β-Dibromo-5α-cholestane- 3β,4β-diol (X) with alkali gave 6β-bromo-4β,5-epoxy-5β-cholestan-3β-ol (IXa), which was oxidized to non-crystalline 6β-bromo-4β,5-epoxy-5β-cholestan-3-one (XIII), characterized as the crystalline 3,3-dimethyl ketal (XIIa). Cleavage of (II) with hydrogen bromide in acetic acid gave 4,6β-dibromocholest-4-en-3-one (V) via the isomeric bromohydrins (IVa) and (IVb). Compound (XIII) yielded (V) directly. Sodium borohydride reduction of (I) gave cholesterol in high yield, while reduction with lithium tri-t-butoxyaluminium hydride afforded cholest-4-en-3-one (52%), cholesterol (30%), and cholest-4-en-6β-ol-3-one (7%).

scholarly journals Melanin Biosynthesis in Cryptococcus neoformans

1998 ◽  
Vol 180 (6) ◽  
pp. 1570-1572 ◽  
Author(s):  
Peter R. Williamson ◽  
Kazumasa Wakamatsu ◽  
Shosuke Ito
Keyword(s):  
Hydrogen Peroxide ◽  
Cryptococcus Neoformans ◽  
Oxidative Coupling ◽  
Hydriodic Acid ◽  
Peroxide Oxidation ◽  
Alkaline Hydrogen Peroxide ◽  
Melanin Biosynthesis ◽  
Permanganate Oxidation ◽  
Catecholamine Oxidation ◽  
Chemical Evidence

ABSTRACT Pigment production by Cryptococcus neoformans is virulence associated. Dopamine- and 3,4-dihydroxyphenylalanine–melanin products were identified after acidic permanganate oxidation, alkaline hydrogen peroxide oxidation, or hydrolysis with hydriodic acid. These data provide direct chemical evidence for the formation of eumelanin polymers by catecholamine oxidation by laccase alone followed by oxidative coupling of dihydroxyindole.

The Reactions of Lignins with High Temperature Hydrogen Peroxide Part 2. The Oxidation of Kraft Lignin

Holzforschung ◽  
1999 ◽  
Vol 53 (3) ◽  
pp. 277-284 ◽  
Author(s):  
J.F. Kadla ◽  
H.-m. Chang ◽  
H. Jameel
Keyword(s):  
Hydrogen Peroxide ◽  
High Temperature ◽  
Molecular Oxygen ◽  
Kraft Lignin ◽  
Phenolic Hydroxyl ◽  
Hydroxyl Groups ◽  
Peroxide Oxidation ◽  
Alkaline Hydrogen Peroxide ◽  
Phenolic Hydroxyl Groups ◽  
Increasing Temperature

Summary A technical pine kraft lignin was subjected to alkaline hydrogen peroxide oxidation in the presence of DTMPA and molecular oxygen at various temperatures. In the presence of DTMPA the lignin was found to undergo increasing levels of oxidation and degradation with increasing temperature. At 110°C over 80% of the kraft lignin was degraded. Analyses of the degraded lignins indicated that both phenolic and nonphenolic lignin moieties were degraded. At 90°C the addition of molecular oxygen resulted in further lignin demethoxylation, but did not decrease the amount of phenolic hydroxyl groups or hydrogen peroxide consumed. In the absence of DTMPA the hydrogen peroxide was rapidly degraded, and accompanied by only minimal lignin oxidation.

Michael Addition of Thiols to Sugar Enones. Synthesis of 3-Deoxy-4-Thiohexopyranosid-2-uloses as Key Precursors of 3-Deoxy- and C-2 Branched-Chain 4-Thiosugars

2002 ◽  
Vol 55 (2) ◽  
pp. 155 ◽  
Author(s):  
M. L. Uhrig ◽  
O. Varela
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Michael Addition ◽  
Ammonium Acetate ◽  
Borohydride Reduction ◽  
Nuclear Magnetic Resonance Spectra ◽  
13C Nuclear Magnetic Resonance ◽  
Good Yielding ◽  
Sodium Borohydride Reduction ◽  
Branched Chain ◽  
Sulfur Containing

Benzyl and 2-propyl 6-O-acetyl-3,4-dideoxy-α -D-glycero-hex-3-enopyranosid-2-uloses (2) and (3) were readily prepared by the tin(IV) chloride-promoted glycosylation of glycal (1). The enone system of (2) and (3) underwent a highly diastereoselective Michael addition of thiols (ethanethiol, propane-2-thiol, and benzenemethanethiol) to afford the sulfur-containing hexopyranosid-2-ulose derivatives (4a-c) and (5a-c) in good yields. Sodium borohydride reduction of the carbonyl functionalities of (4b,c) and (5b) led to the corresponding 3-deoxy-4-thiohexopyranosides having the D-xylo (6b), (6c), and (8b) or the D-lyxo (7b), (7c), and (8c) configuration. Standard acetylation of these compounds gave the corresponding per-O-acetyl derivatives (10b), (10c), and (12b) and (11b), (11c), and (13b), useful for confirming all the previous configurational assignments by means of their 1H and 13C nuclear magnetic resonance spectra. Furthermore the 2-ulose (5b) proved to be a key intermediate for the synthesis of C-2 branched-chain 4-thiopyranosides, such as (16). The latter was synthesized by a good yielding ammonium acetate-catalysed Knoevenagel-type condensation of malononitrile with (5b).

Sodium Borohydride Reduction of 1-Acyl-1,2(1H)-Diazepines and their Iron Tricarbonyl Complexes. Some Reactions of 2,3-Dihydro-1,2(1H)-Diazepines

1975 ◽  
Vol 53 (4) ◽  
pp. 519-528 ◽  
Author(s):  
Takashi Tsuchiya ◽  
Victor Snieckus
Keyword(s):  
Sodium Borohydride ◽  
Sodium Methoxide ◽  
Acetyl Derivative ◽  
Borohydride Reduction ◽  
Deuterium Incorporation ◽  
Sodium Borohydride Reduction ◽  
Iron Tricarbonyl

Sodium borohydride reduction of the 1,2(lH)-diazepines 1a-e and 7, and the 1,2(1H)-diazepine iron tricarbonyl complexes 4a–b provides the 2,3-dihydro-1,2(1H)-diazepines 2a–e and 8, and the (2,3-dihydro-1,2(1H)-diazepine)Fe(CO)3 derivatives 5a–b, respectively. Fe(CO)3 complexes 5a and 6a may be also directly obtained from the 1,2(1H)-diazepines 2a and 3a, respectively. A number of diacylated compounds (3a–c, 6a–b, and 9) are prepared some of which (2a, 3a, 8, and 9) are readily converted into their corresponding (4 + 2)π cycloadducts (14a–d). Treatment of the borohydride reduction products 2a–c with sodium methoxide in methanol gives the 3,4-dihydro-1,2(2H)-diazepines 15a–c. Acetylation of 15a affords the 2-acetyl derivative 16a which may also be prepared by sodium methoxide deacetylation of either 3a or 9. 2-Tosyl-3,4-dihydro-1,2(2H)-diazepine (18) is obtained from 2a by a similar tosylation and deacetylation sequence. When either 2a or 3a are subjected to sodium methoxide in methanol-O-d, compounds 15a and 16a, respectively, are produced which show high deuterium incorporation at C4 and C6 (n.m.r. analysis). Photolysis of the 2,3-dihydro-1,2(1H)-diazepines 2a, 3a, 8, and 9 and the 3,4-dihydro-1,2(2H)-diazepine 16a affords the unstable 2,3-diazabicyclo[3.2.0]hept-6-ene 23a, 23b, 25a, and 25b and 1,2-diazabicyclo[3.2.0]hept-6-ene 27 derivatives, respectively. Treatment of either 25a or25b with sodium methoxide results cleanly in N2-deacylation to give compound 26.

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