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. Author manuscript; available in PMC: 2014 Sep 30.
Published in final edited form as: Synthesis (Stuttg). 2014 Jun 1;46(11):1539–1546. doi: 10.1055/s-0033-1340982

Table 2.

Reaction of α-Ketoamides 1 with α,β-Unsaturated Aldehydes 2

graphic file with name emss-60520-t0008.jpg
Producta R1 R2 R3 Yieldb (%) eec,d (%)
4a Ph Ph Ph 63 97
4b Ph Ph 4-MeOC6H4 51 89 (91)
4c Ph Ph 4-ClC6H4 34 85 (95)
4d Ph Ph 2,3-(OCH2O)C6H3 56 84 (87)
4e 4-MeOC6H4 Ph Ph 66 92 (91)
4f 3-ClC6H4 Ph Ph 69 91 (95)
4g 4-O2NC6H4 Ph Ph 58 95
4h Ph 2-MeC6H4 Ph 70 88
4i Ph 4-ClC6H4 Ph 71 95
a

Reaction conditions: 0.3-mmol scale using α-ketoamide 1 (1 equiv), α,β-unsaturated aldehyde 2 (2 equiv), NaOAc (20 mol%), 3e (20 mol%), CH2Cl2 (1 mL), r.t. All the products were obtained as a single diastereomer.

b

Yield of isolated 4a–i.

c

Determined by HPLC on a chiral stationary phase.

d

Values in brackets correspond to the results obtained with the catalyst (R)-3e. For HPLC determination of the enantiomeric excess, the products 4b–i were transformed into the corresponding α,β-unsaturated ethyl ester.