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5-氨基-4-氨甲酰基咪唑和苯甲酰基异硫氰酸酯生成硫脲，硫甲基化后氨基取代，碱催化关环制备鸟嘌呤的反应。此反应也被称为Yamazaki–Clausen反应。此反应也可通过Cu(II)催化关环。
反应实例
1-[(2-Hydroxyethoxy)methyl]5-[(thiocarbamoyl)-amino]-1-imidazole-4-carboxamide (5). Amine (44 g, 182 mmol) and benzoylisothiocyanate 2 (29.7 g, 182 mmol) were refluxed inMe2COfor 1 h.MeOH (430 mL) and K2CO3 (14.9 g, 108 mmol) in water (45 mL) were added, the mixture was heated to reflux
for 4 h and the pH adjusted to 8 (AcOH) at 0 C. Filtration afforded 39.2 g of 5 (85%), mp 181–183 C.
9-[(2-Hydroxyethoxy)methyl]guanine (6). Thiourea 5 (10 g, 38.6 mmol) was added to CuSO4 (7 g, 44 mmol) in 6N NaOH (80 mL) and stirred for 4 h. Filtration, acidification (HOAc), refluxing for a few min and cooling to 0 C, filtration and recrystallization (water, charcoal) afforded 7.8 g of 6 (85%),
mp 250 C dec.
【Clausen EP, J Org Chem, 1991, 56, 2136】
相关文献
1 Yamazaki A J Org Chem 1967 32 1825
2 Yamazaki A J Heterocycl Chem 1978 15 353
3 Townsen LD J Org Chem 1986 51 1065, 1277
4 Clausen EP J Org Chem 1991 56 2136
5 Nagai T Org Prep Proced lnt 1993 25 388
6 Kochergin PM Chem Hetero Comp 1995 31 337
7 Kim K Tet Lett 2000 41 3573 | 
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