催化加氫和化學(xué)還原法均可用于疊氮的還原，常用的催化加氫催化劑為Pd/C, Raney Ni, 當(dāng)分子內(nèi)有對氫化敏感的鹵素時(shí)，可用PtO2作催化劑。化學(xué)還原最溫和的條件是使用三苯基膦在濕的四氫呋喃中還原，當(dāng)然LAH也可用于該還原。
1，通過 Pd/C 催化劑催化加氫還原烷基疊氮示例
A solution of the material (6.42 g, 19.6 mmoles) dissolved in ethanol (128 mL) was stirred for 1 hour in the presence of 10 percent w/w palladium-on-charcoal (1.67 g) in an atmosphere of hydrogen under atmospheric pressure. At the end of this time, the rection mixture was filtered and the filtrate was concentrated by evaporation under reduced pressure. The resulting crystalline residue was recrystallized from diethyl ether, to afford 4.90 g of the title compound, melting at 104~105 °C.
2，通過 Pd/BaSO4 催化劑催化加氫還原烷基疊氮示例
Palladium/barium sulfate catalyst (0.3 g) was added to a solution of the starting material (6.0g, 32.8 mmols) in ethanol (40 mL) and 0.5N hydrochloric acid (40 mL). Hydrogenation takes place at about 60 psi for 2 hours. After filtration, the volume is concentrated to about 30 mL. When the PH is brought to 6.5 with ammonia, the amino acid separates as a whitepowder. After washing with ethanol/water and drying, 3.5 g of the productwas obtained.melting at 283~285 °C.
3，通過 PtO2 催化劑催化加氫還原烷基疊氮示例
Platinum oxide (14 mg, 0.062 mmol) was added to a solution of the starting material (138 mg,0.5 mmol) in MeOH (4 mL). This mixture was hydrogenated in an atmosphere of hydrogen using a hydrogen filled balloon for 3 h at room temperature. The catalyst was filtered through a bed of CELITE diatomaceous earth and washed with MeOH. The filtrate was concentrated to give the title compound as oil.
4，通過 Raney Ni 催化劑催化加氫還原烷基疊氮示例
The material (21.7 g, 74.5 mmols) was dissolved in methanol (325 mL). Triethyl- amine (9.5 mL) and subsequently hydrazine hydrate (13.5 mL) was added. Then 10 g of raney-nickel was added portionwise to the reaction solution under agitation at room temperature. After three hours, the addition of raney-nickel is completed, the reaction mixture is agitated for another one hour, then the raney-nickel is filtered off. The filtrate was evaporated under vacuum, the residue was dissolved in methylene chloride and the solution is washed with water and sodium chloride solution (10%). Subsequently, the organic phase was dried over sodium sulfate, filtered and evaporated. 17.1 g of the product was obtained.Its dihydrochloride has a melting point of 209~213 °C.
5，通過 PPh3-THF-H2O 體系還原烷基疊氮示例
To a solution of 1.1 g (5.9 mmol) 8-azidomethyl-1,6-napthyridine in 20 mL THF was added 2mL H2O and 3 g PPh3. The resulting solution was allowed to stir overnight at room temperature, then concentrated in vacuo. Purification by flash chromatography (50×140 mm silica gel, linear gradient 5-20percent (10 percent NH4OH in MeOH:CH2Cl2) yielded the desired product.
6，通過 LAH 還原烷基疊氮示例
A solution of the material (10 g, 32.9 mmols) in dry tetrahydrofuran (100 mL) was added dropwise to a stirred suspension of lithium aluminium hydride (4 g, 0.1 mol) in tetrahydrofuran (200 mL) under nitrogen. The resulting mixture was stirred at room temperature for 1 h and quenched with water (4 mL), followed by 15 percent sodium hydroxide (4 mL) and water (12 mL). The mixture was then filtered and the residue washed with tetrahydrofuran (50 mL). The combined filtrate was evaporated to give the title compound (7.5 g, 82% yield) as a pale pink oil.
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