A new, practical route to enoxysilanes is described from simple enolizable aldehydes or ketones, using the trimethylchlorosilane-sodium iodide—tertiary amine reagent in acetonitrile. From certain aldehydes, an onium intermediate has been isolated. A conformational study of this onium intermediate and a thermal unimolecular syn-elimination process may explain the stereoselectivity of the reaction. Such
The wittig rearrangement as a practical method for aldehyde synthesis
作者:Manfred Schlosser、Sven Strunk
DOI:10.1016/s0040-4020(01)80095-8
日期:1989.1
If the rearrangement of metalated allyl ethers 2 (or 4) is accomplished in the presence of potassium tert-butoxide, primary alkyl groups preferentially migrate to the unsubstituted allylic terminus (γ-position). Enolates 7 and 1-vinylalcoholates 6 (by alkyl migration to the α-position, adjacent to the oxygen atom) are produced in an approximate ratio of 9:1. Because of the endo-configuration of their
Copper-catalyzed conjugate addition of the Grignard reagents in the presence of Me3SiCl and HMPA proceeds in much higher yield than the reaction of conventional organocopper reagents and shows very good regio-, stereo-, and chemoselectivities.
Trialkylsilyl chlorides, particularly in combination with hexamethylphosphoramide or 4-dimethylaminopyridine, dramatically accelerates the conjugate addition of catalytic and stoichiometric organocopperreagents onto enones, enals, and enoates, in which very high degrees of stereo- and chemoselectivities were observed.
A Practical Method for the Preparation of Trimethylsilyl Enol Ethers
作者:Ji-Mao Lin、Ben-Sheng Liu
DOI:10.1080/00397919708004194
日期:1997.3
Abstract In the mixed system of chlorotrimethylsilane/triethyl amine/N,N-dimethylformamide/potassium iodide/petroleum ether, aldehydes or ketones are silylated to silyl enolethers at room temperature. The N,N-dimethylformamide / potassium iodie layer can be used as circulating liquor for many times. The yields are high.