An Efficient Deoxygenation of Heteroaromatic N-Oxides Using Zinc Dust/Ammonium Formate Reagent System

Abstract

Heteroaromatic N-oxides were readily and selectively deoxygenated to the corresponding bases with zinc/ammonium formate reagent system.     

Mild and Efficient Deoxygenation of Amine-N-oxides with Titanium Tetrachloride-Indium System

Abstract

TiCl₄/In system was found to be a new reagent for deoxygenation of various amine-N-oxides to the corresponding amines in good to excellent yields under mild conditions.     

Two Unusual Carbohydrate Reactions: Nucleophilic Ring Opening of an Anhydrosugar and Reductive Elimination with Co‐occurring Hydrogenation

Treatment of the 1,6‐anhydrosugar epoxide 5 with a cyano‐Gilman cuprate [(CuCN (6 eq.), MeLi (12 eq.)] surprisingly led to the open chain rearranged (2S,3R)‐1,2‐dihydroxy‐3,6‐dimethylheptan‐4‐one (7), structurally confirmed by conversion to the corresponding diacetate 8. Another unusual reaction was found by hydrogenation of the 2‐tosyl‐1‐bromosugar 11, leading in one operation to the twofold deoxygenated chiral pyran derivative 14. This procedure might prove to be useful in the rapid deoxygenation of sugar derivatives.     

Total Synthesis of α-Elvucitabine

Total synthesis of α-elvucitabine was achieved in 26% overall yield by a concise nine-step procedure starting from L-lyxose, with trimethylsilyl trifluoromethaneoulfonate (TMSOTf)–mediated stereocontrolled α-N-glycosidation and olefination through Barton–McCombie deoxygenation being the key steps, and the stereochemistry of the product was determined by nuclear Overhauser effect spectroscopy.     

Deoxygenation of Aromatic Ketones Using Transfer Hydrogenolysis with Raney Nickel in 2-Propanol

Aryl ketones are readily deoxygenated to their corresponding aryl alkanes upon treatment with Raney nickel catalyst in boiling 2-propanol.

Mild and Efficient Deoxygenation of Sulfoxides with a WCl6/Indium System

Dialkyl, diaryl, and aryl alkyl sulfoxides can be rapidly converted to the corresponding sulfides with a WCl₆/In system in excellent yields under mild conditions.     

A new method of synthesis of substituted 1-(1H-imidazole-4-yl)-1H-1,2,3-triazoles and their fungicidal activity

Based on the deoxygenation reaction of 1-(1-tert-butyl-3-nitroazetidine-3-yl)-1H-1,2,3-triazoles a new method for the synthesis of substituted 1-(1H-imidazole-4-yl)-1H-1,2,3-triazoles has been developed. Fungicidal activity of these compounds has been investigated at a range of phytopathogenic fungi.     

A mild,efficient, and selective procedure for the deoxygenation of sulfoxides with the TaCl5/indium system

The TaCl₅/In system was found to be a new reagent for reducing a wide range of structurally diverse sulfoxides to the corresponding sulfides with high yields under mild conditions. This protocol is chemoselective and tolerates several functional groups, such as Br, Cl, OCH₃, CHO, and CH = CH₂.     

Depolymerization of Organosolv Lignin over Silica-alumina Catalysts

E cient conversion of lignin to fine chemicals and biofuel become more and more attractive in biorefinery. In this work, we used a series of silica-alumina catalysts (i.e., SiO₂-Al₂O₃, HY, Hβ, and HZSM-5) to degrade lignin into arenes and phenols. The relationship between the catalyst structure and lignin depolymerization performance was investigated. The results showed that both acidity and pore size of the catalyst could in uence the conversion of lignin. In the volatilizable product, phenols were identified as the main phenolic monomers via gas chromatography-mass spectrometer. SiO₂-Al₂O₃ was the most effcient catalyst, giving 90.96% degree of conversion, 12.91% yield of phenols, and 2.41% yield of arenes in ethanol at 280℃ for 4 h. The Fourier transform infrared spectroscopy and ¹H nuclear magnetic resonance spectroscopy analysis demonstrated that deoxygenation and alkylation occurred in this process. The effect of solvents was also investigated and the results showed that ethanol was the most effcient solvent.     

Synthesis of 7,9-dideoxybaccatin IV analogs from sinenxan A

Sinenxan A, a taxoid isolated from callus tissue cultures of Taxus yunnanensis was converted into 13-oxo-7,9-dideoxy-2-debenzoyl-2-acetyl-baccatin IV and 7,9-dideoxy-2-debenzoyl-4-deacetyl-baccatin IV, a key framework of 1,7,9-trideoxypaclitaxel. Several special steps in this transformation are worthy of note: (1) deoxygenation by treatment with hypophosphorous acid at C-14 position; (2) a highly regioselective O-deacetylation of taxanes at C-5 position; and (3) stereoselective reduction of the 13-carbonyl group by transannular assistance from the C-4-hydroxyl.