Methylephedrine-mediated asymmetric

Carreira and co-workers developed a highly efficient enantioselective addition of terminal alkynes to aldehydes giving propargyl alcohols by the mediation of zinc tri-flate and N-methylephedrine [17]. This reaction serves as a convenient and powerful synthetic route to a wide variety of enantioenriched allenes via propargyl alcohols. Dieter and Yu applied this alkynylation to the asymmetric synthesis of allenes (Scheme 4.12) [18]. Reaction of phenylacetylene with isobutyraldehyde afforded the propargyl alcohol in 80% yield with 99% ee, which was mesylated to 49 in quantitative yield. Reaction of 49 with the cyanocuprate 50 afforded the desired allene 51 with 83% ee. 

Chiral silyl ketene acetals derived from (lS,2/ )-yV-methylephedrine (168), known to exhibit high levels of syn-anti and diastereofacial selectivities in the aldol condensation, have been used by Gennari et al. in TiCU-mediated imine condensations for the asymmetric synthesis of 3-lactams (Scheme 34) 32. 33 p.j mino esters (169) are produced in these reactions, and are characterized by their sub-... 

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