Cyanosilylation of Aldehydes and Ketones Catalyzed by Nanocrystalline Magnesium Oxide

Abstract

Cyanosilylation of various aldehydes and ketones with TMSCN proceeded smoothly under mild conditions to give the corresponding cyanohydrin trimethylsilyl ethers in the presence of nanocrystalline magnesium oxide. The cyanohydrin trimethylsilyl ethers of aldehydes produced cyanohydrins in good to high yields on treatment with 2 N HCl. ²⁹Si NMR spectral evidence proved that the reaction proceeds through the hypervalent silicate species by coordination to O²⁻/O⁻ (Lewis basic site) of nanocrystalline magnesium oxide.

Keywords:

• Aldehydes
• cyanohydrins
• cyanohydrin trimethylsilyl ethers
• cyanosilylation
• ketones
• nanocrystalline magnesium oxide
• trimethylsilyl cyanide

ACKNOWLEDGMENTS

K. M. thanks Council of Scientific and Industrial Research, India, for the award of his senior research fellowship. The authors thank Dr. A. V. S. Sharma, NMR Division, Indian Institute of Chemical Technology, for providing the ²⁹Si NMR.

Notes

^a Isolated yield.

^b NA-MgO.

^c CM-MgO.

^d Sil-NAP-MgO.

^e Fourth cycle.

^f Without catalyst.

^a Reaction conditions: (i) aldehyde 1 (1 mmol), TMSCN (1.5 mmol), NAP-MgO (0.1 g), and THF (3 mL) at room temperature; (ii) 2N HCl (2 mL) at room temperature.

^b Isolated yield.

^a Reaction conditions: acetophenone 3 (1 mmol), TMSCN (2 mmol), NAP-MgO (0.1 g), and THF (3 mL) at room temperature.

^b Isolated yield.

^a Reaction conditions: acetophenone 3a (0.1 mmol), TMSCN (0.2 mmol), catalyst (0.01 g), and CDCl₃ (0.5 mL) at 25 °C.