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Please login to access the full content or check if you have access via2.12.2.5 Reactions with Chiral Tin Catalysts
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Liu, L.; Wang, D.; Li, C. -J., Science of Synthesis: Stereoselective Synthesis, (2011) 2, 606.
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).
Meeeee 88 Meeeeeeeee Meeeeeeee Meeee Meeeeeee Meeeeeeee ee e Meeeee Mee(MM)–Me-eeeee Meeeeee[88]
Meeeeeeeeeee Meeeeeeee
eeee-Meeee (8M,8M)-8-Meeeeee-8-(eeeeeeeeeeeeeee)-8-eeeeeeeeeeeeeeeeeee (88); Meeeeee Meeeeeeee:[88]
Me ee eeee-eeeee 8-eM eeee eeeeeeeeee e eeeeeeee eeeeeee eee eee eeeee, ee ee eeeee eeeeeeeeee eee, (M,M)-eee(eeeeeeeeeeeeeeeeeeeee)eeeeeeee (88; 88.8 ee, 8.888 eeee) eee Me(MMe)8 (88.8 ee, 8.888 eeee). Mee eeeee eee eeeeee eeee e eeeeee eee, eeeeeee eeee eee eeeee eeeeeeeeee eee, eee eeeeeee eeee MM8Me8 (8.8 eM). Mee eeeeeeeee eeeeeeeeee eee eeeeeee eeeeeee eee 8 e ee eeee e eeeeee eeee. Mee eeeeeeee eeee eee eeeeee ee −88 °M, eee eeeeee eeeeeeee (88 µM, 8.88 eeee) eee eeeee, eeeeeeee ee eee M-eeeee eeeeee eeeeee 88 [eeeee (M/M) 88:8; 888 µM, 8.88 eeee] eeeeeee eeee M-eeee-eeeee eeeeeeeeeeeeee. Mee eeeeeeeee eeee eee eeeeeee ee −88 °M eeeee eee eeeeeeee eee eeeeeeeeee eeeeeeee (8–88 e), ee eeeeeeeeee ee MMM (Me8M/MM8Me8 8:88). Mee eeeeeee eee eeee eeeeeeee eeeeeee e 8.8 × 8 ee eeee (eeeeee eee) eeee Me8M (8 eM). Meeeeeeeeeeee ee eee Me8M eeee eeee eee eeeee eeeee eeeee, eeeee eee eeeeeeeee ee MMM (8 eM) eee 8 M MMe (8.8 eM). Meeee eeeeeeee ee ee eee 8–8 e, eeee eeee eee eeeeee eeee e eeeeeeeeee eeeeee eee eeeeeee eeee Me8M (88 eM) eee M8M (88 eM). Meeee eeeeee, eee eeeeeee eeeee eee eeeeeeeee, eee eee Me8M eeeee eee eeeeee eeee eee. ee MeMMM8 (88 eM) eee eeeee (88 eM). Mee eeeeeeeee Me8M eeeee eee eeeee (Me8MM8), eeeeeeee, eee eeeeeeeeeeee ee eeeeeee eee eeeeeee eeeee. Meeeeeeeeeee ee eeeee eeeeeeeeeeeeee (MeMMe/eeeeee 8:8 ee 8:8) eeeeeeee eee eeeeeee ee e eeeeeeeee eee; eeeee: 888 ee (88%); ee (eeee/eee) 88:8; 88% ee (eeee).
References
[18] | Meeeeeeee, M.; Meeeeeeee, M.; Meeeee, M.; Meeeee, M., Meee. Meee., (8888), 888. |
[31] | Meeee, M. M.; Meeeeeeee, M. M.; Meeeee, M. M.; MeeMeeeee, M. M. M., M. Me. Meee. Mee., (8888) 888, 8888. |