渝偲醫藥關于：三苯甲基保護的胺基的脫保護介紹

時間：2022/11/18閱讀：469

Trt容易用酸脫去，如用HOAc或50%（或75%）HOAc的水溶液在30℃或回流數分鐘順利除去。這時N-Boc和O-But可以穩定不動。其他如HCl/MeOH、HCl/CHCl3、HBr/HOAc和TFA都能很方便的脫去Trt，用HCl/MeOH處理Trt-Lys(Trt)OCH3可以得到Lys(Trt)OCH3，說明側鏈上的Trt比α-Trt 對酸更穩定一些。Cys(Trt)、His(Trt)和Try(Trt)等的側鏈上的N-Trt比Nα-Trt 對酸穩定，因此可以采用適當的酸解條件選擇性脫去Nα-Trt而保留側鏈上的N-Trt。

Trt對酸的敏感程度還隨所用的酸的不同而異，例如Trt對醋酸比較敏感，在80%的醋酸中，Trt的脫除速度大約比Bpoc快7倍，比Boc快21，000倍，因而可以在Boc或Moz存在下選擇性地脫去Trt。但如用0.1MHBr/HOAc為試劑，Trt脫去速度反而慢于Boc和Moz。

Trt也能被催化氫解脫去，但脫去速度比O-芐基和N-Cbz要慢得多。根據所用試劑和脫去方法得不同，Trt被分解所形成的產物也不同（見下式）。

一、TFA脫去三苯甲基示例

M. Firouz Mohd Mustapa,RichardHarris,Nives Bulic-Subanovic et al., J. Org. Chem., 2003,21, 8185; S. Vinay, M. Mizio etal., Tetrahedron, 2002, 44, 9101

Compound 1(3.5 g, 4.6 mmol) was treated with a 5%solution of trifluoroacetic acid (1.4 mL, 18 mmol, 4 equiv) in CHCl3(27 mL) under inert conditions for 4 h. The resultingsolution was diluted with CHCl3(200 mL) andwashed with sodium hydrogen carbonate (5% aq w/v, 2 × 75 mL) and water (2 × 50mL). The solvent was removed in vacuo. The material was then redissolved in CHCl3(20 mL) and MeOH (20 mL), and the solvents were againremoved in vacuo to yield compound 2(2.1 g, 87%) as a pale yellowliquid.

二、 TFA-TIS脫去三苯甲基示例

Swall, Vinay; Matteuccl et al., Tetrahedron, 2002, 58(44), 9101-9110

Compound 1(2.0 g, 2.71 mmol) was stirred with TFA(4.9mL), CH2Cl2 (4.9mL) and TIS (0.2 mL) for 1 h. Solventwas removed in vacuo and the residue purified by column chromatography (SiO2, MeOH/CHCl3, 1:9 v:v) toafford compound 2(1.16 g,91%) as a white solid.

三、TFA-Et3SiH脫去三苯甲基示例

Pickersgill, I.Fraser; Rapoport, Henry; J. Org. Chem., 2000,65(13),4048-4057

To a stirred solution of compound 1(3.34 g, 3.82 mmol) and triethylsilane (0.64 mL, 4.01mmol) in CH2Cl2(16 mL) cooled to 0 °C was added dropwise TFA (16 mL). Theresultant colorless solution was allowed to warm to rt, with stirring continuedfor 1 h. The solvents were evaporated, the residue was triturated with hexanes(5 x 50 mL), the hexane extracts were discarded, and the oily residue waspartitioned between CHCl3/IPA (250 mL, 3/1) and 1 M NaOH (precooled to 0 °C,100 mL). The aqueous phase was extracted with further portions of CHCl3/IPA (2 x 200mL, 3/1), and the combined organic phase was dried, filtered, and evaporated togive compound 2(2.04 g, 100% crude yield) as a pale yellowoil.

4.1.2.4 HOAc脫去三苯甲基示例

Vago, Istvan; Kalaus, Groergy et al., Heterocycles,2001, 55(5), 873-880

0.85 g(2 mmol) of compound 1 wasdissolved in the mixture of 20 mL of acetic acid and 0.5 mL of water. The solutionwas heated under argon at 60 oC for 1 h, and then allowed to cool to rt. Theresulted dark solution was diluted with 200 mL of water; the triphenylmethanolwas removed by extraction with ether. The pH of the watery phase was adjustedto a value of 8 with sodium carbonate solution, extracted with dichloromethane;the extract was dried with magnesium sulfate, evaporated to dryness in vacuumtogive, compound 2(0.24 g,64 %) as unstable brown oil.

4.1.2.5 TBS和Boc官能團存在下用BF3-HOAc脫去三苯甲基示例

Pickersgill, I, Fraser; Rapoport, Henry; J. Org. Chem., 2000, 65(14),4048-4057

To a solution of 32 (2.67 g, 3.98 mmol) in CH2Cl2(27 mL) cooled to 0 °C were added glacial acetic acid (6.7 mL)and BF3.Et2O (0.529 mL, 4.17 mmol) dropwise, and the mixture wasstirred at 0 °C for 2 h.Cold (0 °C) 1 M NaOH (160 mL) was added and the mixturepartioned between CHCl3/IPA (320 mL, 3/1) and cold (0 °C) 1 M NaOH (66 mL), followed by extraction with further portions ofCHCl3/IPA (2 x 160 mL, 3/1). The combined organic phase wasdried, filtered, and evaporated to a residue which was chromatographed (CH2Cl2/MeOH,19/1 to 9/1) to give 33 (1.50 g,88%) as a colorless oil: [α]22D= +3.1 (c = 1.0,CHCl3).

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