The metalation-silylation of O-trimethylsilyl aldehyde cyanohydrins
摘要:
The metalation-trimethylsilyation of O-trimethylsilyl (saturated) aldehyde cyanohydrins was achieved by in situ treatment with LDA and trimethylchlorosilane at -78-degrees-C. C-Silyl products (O-trimethylsilyl acylsilane cyanohydrins) generally predominated, but N-silyl derivatives (ketenimines) were found in some instances. LDA could be added across the C = N bond of the latter. The metalation-trimethylsilylation of O-trimethylsilyl benzaldehyde cyanohydrin could only be effected if 2 equiv of trimethylchlorosilane were employed per equivalent of cyanohydrin anion.
Cyanosilylation of aldehydes and ketones. A convenient route to cyanohydrin derivatives
作者:D. A. Evans、L. K. Truesdale、G. L. Carroll
DOI:10.1039/c39730000055
日期:——
A wide variety of aldehydes and ketones reacts with trimethylsilyl cyanide under both thermal and catalytic conditions to give α-silyloxy nitriles which may be useful intermediates and protective groups in organic synthesis.
A General Synthesis of 3,5-Dihalo-2<i>H</i>-1,4-oxazin-2-ones from Cyanohydrins
作者:Lieven Meerpoel、Georges Hoornaert
DOI:10.1055/s-1990-27049
日期:——
In a novel approach starting from O-trimethylsilyl protected or unprotected cyanohydrins and oxalyl chloride or bromide, a series of unknown 6-substituted 3,5-dihalo-2H-1,4-oxazin-2-ones were prepared. The method was shown to be efficient for various types of cyanohydrins; however cyclization was not obtained with cyanohydrins containing bulky substituents, electron-rich aryl or heteroaryl groups. A mechanism is proposed.
Synthesis of 3,5-dihalogeno-2H-1,4-oxazin-2-ones from cyanohydrines
作者:L. Meerpoel、G. Hoornaert
DOI:10.1016/s0040-4039(00)99196-2
日期:——
The title compounds were obtained on treatment of cyanohydrines of aliphatic and aryl aldehydes with oxalyl chloride or bromide in chlorobenzene at 90°C. Evidence for their structure is given by their spectroscopic data and by the Diels Alder reaction of a and g with acetylenic dienophiles to yield substituted pyridines. Cycloaddition was also observed with ethene.
Two routes can offer the first stannylene cyanide [(L)SnCN] (5); the substitution reaction of either stannylene amide [(i-Bu)2ATISnN(SiMe3)2] (3) or stannylene pyrrolide [(i-Bu)2ATISn(NC4H4)] (4) using an excess of trimethylsilyl cyanide (L = aminotroponiminate (ATI)). Using 0.1–2.0 mol% of compound 5, catalytic cyanosilylation of a variety of aliphatic and aromaticaldehydes was achieved at rt−50 °C