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Asymmetric Synthesis of α-Substituted Aldehydes
B. M. Trost*, T. Zhang
Stanford University, USA
24 April 2007 (online)
Optically active aldehydes 5 were prepared from simple starting materials 1 and 2, using Pd asymmetric allylic alkylation-alkene isomerization-Claisen rearragement (Pd-AAA-ICR). The key step of the sequence relied on a chemoselective olefin isomerization of the more substituted alkene in 4. Indeed, using modified conditions from previous work (S. G. Nelson et al. J. Am. Chem. Soc. 2003, 125, 13000-13001), the terminal olefin was left untouched to yield (E)-6, which underwent a thermal Claisen rearrangement to provide chiral aldehyde 5.