Tolerance analysis optimal conditions

Figure 6 Tolerance analysis for optimal conditions when material temperature = 70. Abbreviations LSL, lower spec limit T, target USL, upper spec limit.

The scope of this asymmetric HDAR was evaluated under the optimized reaction conditions using o-benzoquinone diimide 268. Since the hemiaminal 270 was not stable enough for further analysis, PCC (pyridinium chlorochromate) oxidation was employed to produce the more stable quinoxalinones 271. As shown in Scheme 2.41, a variety of aldehydes 253 bearing simple linear or branched a-substituted alkyl groups were well tolerated and excellent enantioselectivities were generally obtained. 

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