Anomalous Z-isomer content in Wittig reaction products from keto-stabilised ylides with ortho-heteroatom substituted benzaldehydes
作者:Peter A. Byrne、Lee J. Higham、Pádraic McGovern、Declan G. Gilheany
DOI:10.1016/j.tetlet.2012.09.123
日期:2012.12
Wittig reactionproducts of keto-stabilised ylides with ortho-substituted benzaldehydes are found to show significantly higher than expected Z-alkene content (up to 50%) compared to analogous reactions of the same ylides with benzaldehyde itself. A cooperative effect is seen whereby the unusual Z-content is further augmented if the ylide bears greater steric bulk in the α′-position. These results are
Synthesis of α,β-Unsaturated α′-Haloketones through the Chemoselective Addition of Halomethyllithiums to Weinreb Amides
作者:Vittorio Pace、Laura Castoldi、Wolfgang Holzer
DOI:10.1021/jo401236t
日期:2013.8.2
A straightforward synthesis of variously functionalized α,β-unsaturated α′-haloketones has been achieved through the chemoselective addition of halomethyllithium carbenoids to Weinrebamides at −78 °C. A comparative study employing the corresponding esters under the same reaction conditions pointed out that the instability of the tetrahedral intermediate formed from the latter is responsible for the