A comparison of the Still–Gennari and Ando HWE-methodologies with α,β-unsaturated aldehydes; unexpected results with stannyl substituted systems

Still–Gennari reactions have been carried out on a range of E- and Z-3-substituted propenals. In all cases, with the exception of Z-3-stannyl systems, good Z-stereoselectivity was observed. By contrast, the Ando procedure gives reasonable Z-stereoselectivity with all systems studied, including those with a cis-disposed stannyl substituent.