氰基引入的新方法:镍催化芳基甲醛(肉桂醛)O-烯丙基肟制备腈

chem 有机方法 2.9K+ 0

文献1报道了一种芳基甲醛/肉桂醛O-烯丙基肟在Ni(cod)2催化下制备腈的方法,该方法操作相对简单,原料易得,底物适用范围广,但是不适用于脂肪醛O-烯丙基肟。

氰基引入的新方法:镍催化芳基甲醛(肉桂醛)O-烯丙基肟制备腈  第1张


底物适用范围
氰基引入的新方法:镍催化芳基甲醛(肉桂醛)O-烯丙基肟制备腈  第2张


氰基引入的新方法:镍催化芳基甲醛(肉桂醛)O-烯丙基肟制备腈  第3张

值得注意的是:该方法对于脂肪族类底物不适合,无法得到相应的腈类化合物。


作者对醛肟氧上取代基类型进行了考察
氰基引入的新方法:镍催化芳基甲醛(肉桂醛)O-烯丙基肟制备腈  第4张

当氧上取代基为烯丙类时,反应效果较好;其它类型的取代基反应效果都很差。


General procedure
Preparation of benzaldehydeO-allyl oxime 1:Sodium acetate (1.5 eq) and O-allylhydroxylamine hydrochloride (1.2 eq) were charged into a round flask. After the addition of MeOH (14 mL) and H2O(1.3 mL) into the flask, benzaldehyde (5.0 mmol) was added dropwise to the mixture at RT. The reaction mixture was stirred at RT overnight. The resulting mixture was concentrated by evaporation and then H2O was added. The resulting aqueous phase was extracted with EA. The combined organic phase was washed with water, brine, dried over MgSO4. After removal of the solvent, the resulting crude mixture was purified by silica gel column chromatography(Hexane/EA) to give benzaldehyde O-allyl oxime.
Preparation of benzonitrile 2: Benzaldehyde O-allyl oxime 1 (1 mmol) and DPEphos (0.1 eq) were charged into a screw cap vialand the vial was taken into a glove box.In the glove box, Ni(cod)2 (0.1eq) and THF (1.2 mL)were added to the vial and the reaction vial was taken from the glove box. The resulting mixture was stirred at 60 ˚C for 17 h. The reaction mixture was allowed to cool to RT and then H2O was added.The resulting aqueous phase was extracted with EA. The combined organic phasewas washed with water, brine, dried over MgSO4. After removal of the solvent, the resulting crude mixture was purified by silica gel column chromatography(Hexane/EA) to givebenzonitrile.
Preparation of (E)-cinnamaldehyde O-allyl oxime 8: Sodium acetate (1.5 eq) and O-allylhydroxylaminehydrochloride (1.2 eq) were charged into a round flask. After the addition of MeOH(8.3 mL) and H2O(0.75 mL) into the flask, cinnamaldehyde (3.0 mmol) was added dropwise to the mixture at RT. The reaction mixture was stirred at RT overnight. The resulting mixture was concentrated by evaporationand then H2O was added.The resulting aqueous phase was extracted with EA.The combined organic phase was washed with brine, dried over MgSO4. After removal of the solvent, the resulting crude mixture was purified by silica gel column chromatography (Hexane/EA) to give (E)-cinnamaldehyde O-allyl oxime.

Preparation ofcinnamonitriles 9: (E)-Cinnamaldehyde O-allyl oxime (1mmol) and DPEphos (0.2 eq)were charged into a screw vial and the vial was taken into a glove box. In the glove box, Ni(cod)2 (0.2 eq) and1,4-dioxane (2.4 mL) were added to the vial and the reaction vialwas taken from the glove box. The resulting mixture was stirred at 100 ˚C for 17 h.The reaction was allowed to cool to RT and then quenched with water. The reaction mixture was filtrated with a pad of celite and additional water was added. The resulting aqueous phase was extracted with EA. The organic phasewas washed with brine and dried over MgSO4. After removal of the solvent, the resulting crude mixture was purified by silica gel column chromatography (Hexane/EA)to give cinnamonitrile.


主要试剂

Ni(cod)2cas号: 1295-35-8
DPEphoscas号: 166330-10-5

参考文献DOI
1
10.1021/acs.joc.9b02705

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