- Enantioselective preparation of N-chirogenic tertiary amine oxides
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We found that PLE can be used as an efficient catalyst for desymmetrization of prochiral tertiary amine N-oxides and demonstrated that they were hydrolyzed by PLE efficiently to afford N-chirogenic tertiary amine oxides up to 99% ee in moderate to good yields.
- Suzuki, Ichiro,Kerakawauchi, Ran,Hirokawa, Takako,Takeda, Kei
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p. 6873 - 6876
(2008/02/12)
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- A mild and efficient cyanosilylation of ketones catalyzed by a Lewis acid-Lewis base bifunctional catalyst
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A new family of bifunctional catalysts (N-oxides-Ti(OiPr)4 (2:1)) containing a Lewis acid and a Lewis base was developed and applied to the catalytic cyanosilylation of ketones. Utilizing rac((1R,2S) and (1S,2R))-1-(2′-pyridylmethyl)-2-diphenylhydroxymethylpyrrolidine N-oxide-titanium (2:1) complex and N-benzyl-diethanolamine N-oxide-titanium (2:1) complex as catalysts, the cyanosilylation products were obtained in 42-97% yield. Based on experimental phenomena and kinetic studies, a catalytic cycle was proposed to explain the remarkable activities of these catalysts. Investigations indicated that rac((1R,2S) and (1S,2R))-1-(2′-pyridylmethyl)-2-diphenylhydroxymethylpyrrolidine N-oxide-titanium (2:1) complex and N-benzyl-diethanolamine N-oxide-titanium (2:1) complex should promote the reaction via a dual activation of the ketone by the titanium and TMSCN by the N-oxide.
- Shen, Yongcun,Feng, Xiaoming,Li, Yan,Zhang, Guolin,Jiang, Yaozhong
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p. 5667 - 5675
(2007/10/03)
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- A mild and efficient cyanosilylation of ketones using in situ generated n-oxides-ti(iPrO)4 complexes as catalysts
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The addition of TMSCN to ketones catalyzed by complex of racemic N-(2′-pyridylmethyl)-2-diphenylhydroxymethylpyrrolidine N-oxide (rac-1) or N-benzyl-N,N-dihydroxyethylamine N-oxide and Ti(iPrO)4 affords the racemic O-TMS cyanohydrins in good to excellent isolated yields (up to 97%) under mild reaction conditions.
- Shen, Yongcun,Feng, Xiaoming,Li, Yan,Zhang, Guolin,Jiang, Yaozhong
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p. 793 - 795
(2007/10/03)
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