Thermal rearrangement of α-hydroxy imines with an α-allyl or an α-propargyl substituent
作者:Jean-Michel Vatele、Daniel Dumas、Jacques Gore
DOI:10.1016/0040-4039(90)80205-z
日期:1990.1
In refluxing diglyme, the title α-hydroxy imines and rearrange cleanly to amino ketones and substituted on the carbon α to nitrogen by an allyl or a propargyl group. In the case of α-hydroxy imine , the migration of the allyl group occurs with an allylic transposition.
Highly Regio- and Stereoselective Allylation of α-Diketones via the Fluorosilicate Route
作者:Rainer Gewald、Mitsuo Kira、Hideki Sakurai
DOI:10.1055/s-1996-4151
日期:1996.1
Allylation of enolizable α-diketones with allyltrifluorosilanes in the presence of triethylamine gave the corresponding tertiary homoallyl alcohols in good yield in a highly regio- and stereospecific manner. The reaction proceeds as diallylation with allyltrifluorosilanes yielding the 1,2-diols with high diastereoselectivity. The more sterically demanding crotyl- and prenyltrifluorosilanes lead exclusively to monoallylated products with the allyl group being added γ-regioselectively. In addition, highly diastereoselective crotylation was observed in the formation of the monoallylated α-hydroxy ketones. Asymmetric α-diketones were generally allylated at the less enolized ketone group except when both diketone and allylsilane were sterically hindered.
EPR Support for the Ketyl Radical-Anion “Triggered” [3,3]-Sigmatropic Rearrangement
作者:Eric J. Enholm、Merle A. Battiste、Maria Gallagher、Kelley M. Moran、Angelo Alberti、Maurizio Guerra、Dante Macciantelli
DOI:10.1021/jo0257748
日期:2002.9.1
New physical evidence to support a ketylradical-anion mechanism for the [3,3]-sigmatropic rearrangement is presented. With use of EPR spectroscopy, spectra are observed that can be attributed to 8, an acyl radical-anion species resulting from a [3,3]-rearrangement; this also functions as a key intermediate in the process. The spectrum of an additional paramagnetic species resulting from further addition