Dondoni甲酰基化反应

2-三甲基硅基噻唑对醛酮或酰氯进行亲核反应得到羟甲基噻唑，接着通过还原水解（MeI/MeOTf ，NaBH4， HgCl2/CuCl2/CuO/AgNO3）生成醛酮或酰氯的甲酰化产物的反应。

2-三甲基硅基噻唑可以看作甲酰基负离子的等价物与亲电性化物反应。可以连续进行两次Dondoni甲酰基化反应用于制备多两个碳的糖类化物。

反应实例

1,3,4,6-Tetra-O-acetyl-2-O-benzyl-L-gulopyranose (7).3 To a cooled (20 C), stirred solution of crude aldehydo-L-xylose diacetonide 5 (3.53 g, 15.3 mmol) in anhyd DCM (60 mL) was added 2-(trimethylsilyl) thiazole 2 (3.2 mL, 19.9 mmol) during 15 min. After 1 h at 0 C and evaporation, the residue in 60 mL anh THF was treated with nBu4NF.3H2O (4.48 g, 15.3 mmol) at r.t. for 30 min and concentrated. The residue was subjected to usual workup and concentration to give antiadduct 6 (4.50 g, 80%) containing 5% of syn isomer. Crystallization from EA-cyclohexane afforded pure 6 (3.42 g, 61% from 5). Benzylation of 6 (BnBr, NaH, DMF) was followed by cleavage of the thiazole ring (N-methylation, reduction, hydrolysis). Final deacetonization (AcOH, H2O) and acetylation

(Ac2O) gave 7.

【Dondoni A， J Org Chem， 1997， 62， 6261】

相关文献

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