| Research Abstract |
Much attention has been focused on the conventional generation of active synthetic intermediates using organometallic reagents which are hard to prepare by other method. We demonstrate that 1,3-elimination of -heteroatom substituted organosilicon compounds can be readily achieved and that non-stabilized azomethine ylides and thiocarbonyl ylide which are the most important 1,3-dipoles from both synthetic and theoretical points of view are obtained very smoothly under mild conditions. this constitutes an unprecedented and expedient route to parent azomthine ylide and thiocarbonyl ylide.
(1) N-(Silylmethyl)aminomethyl ethers and chloromethyl silylmethyl sulfide as azomethine ylide and thiocarbonyl yilde synthous, respectively, readily prepared, undergo the activation of the carbon-oxygen and carbon-chlorine bond selectively by the Lewis acid or cesium fluoride in the presence of electron deficient alkenes, carbonyl compounds and N-heteroaromatics, to give the corresponding pyrrolidines, tetrahydrothiophenes, 1,3-oxathiolanes, and 1,3-thiazolidines in considerably high yield.
(2) We found a convenient preparation and tandem cycloaddition reactions of 2-dimethylaminomethyl-3-trimethylsilylmethyl-1,3-butadiene that serves as 2,2'-biallyl diradical and 2,2'-biallyl zwitterion synthons.
(3) Pentacoordinate allylsiliconates and related compounds, unknown hitherto, can be readily prepared and used as uncleophiles for the highly chemo-, regio- and stereo-selective reduction and allylation.
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