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Kotha–Schollkopf氨基酸合成反應(yīng)

2021.03.10

異氰基乙酸乙酯（EICA）在堿性條件下 (e.g. NaH, t-BuOK, n-BuLi, DBU and Et3N)與C-親電試劑反應(yīng)生成二烷基異氰基乙酸乙酯，接著水解得到α-氨基酸衍生物的反應(yīng)，被稱為Kotha–Schollkopf氨基酸合成反應(yīng)。異氰基乙酸乙酯（EICA）相當(dāng)于甘氨酸等價(jià)物。二鹵代烷烴作為底物可以用于合成環(huán)狀氨基酸衍生物。此反應(yīng)的一個(gè)改進(jìn)法是利用碳酸鉀作為堿，并加入相轉(zhuǎn)移催化劑（四丁基硫酸氫銨），在加熱條件下反應(yīng)進(jìn)行烷基化，操作更加簡便。

反應(yīng)機(jī)理

反應(yīng)實(shí)例

【Tet. Lett., 1998, 39, 4095】

Amino acid (7). To 1 (0.5 mmol) in 20 mL MeCN were added finely powdered K2CO3 (3 mmol), TBAHS (0.1 mmol), and α,α-dibromo-o-xylene 5 (0.5 mmol). The mixture was heated at 70–80℃，until 5 was consumed (TLC). Filtration, washing of the solid with MeCN, filtrate evaporation and chromatography afforded isocyanoester 6 (93%). To the latter (0.16 mmol) in 5 mL abs EtOH at r.t. wasadded a few drops of conc HCl and after a few hours stirring the solution was evaporated. The resultingHCl salt in H2O was washed with ether and NH4OH was added to the aq layer to pH 9–10. Extractionwith EA and workup gave 7 (90%).

【J. Org. Chem., 2000, 65, 1359】

相關(guān)文獻(xiàn)

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