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DOI: 10.1055/sos-SD-202-00309

Liu, L.; Wang, D.; Li, C. -J.Science of Synthesis: Stereoselective Synthesis, (20112606.

In the first example of a catalytic asymmetric Mukaiyama aldol reaction, a catalytic amount of chiral diamine-coordinated tin(II) trifluoromethanesulfonate was used as a chiral catalyst in the addition process.[‌18‌] In 1997, a C2-symmetric chiral ligand (box) was developed.[‌31‌] The ligand was combined with tin(II) reagents and was applied in the asymmetric aldol reaction as a chiral tin(II) catalyst. As shown in Scheme 34, the aldol reaction of α-keto esters (e.g., methyl pyruvate) with substituted sulfanyl enol silanes (e.g., 30) can be catalyzed by the chiral Lewis acid derived from tin(II) trifluoromethanesulfonate and 2,6-bis[(4S)-4-phenyl-4,5-dihydrooxazol-2-yl]pyridine (27, Ph-pybox) to produce the aldol adducts (e.g., 79) with high anti selectivity (anti/syn 99:1) and enantioselectivity (99% ee).

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