Asymmetric transformation of chiral auxiliary-substituted N-acyl-α-dehydro(1-naphthyl)alanines into 3,4-dihydrobenzo[f]quinolinone derivatives via photoinduced electron transfer
摘要:
Electron transfer-initiated photocyclizations of the title compounds [(Z)-1] with an (S)-alanine methyl ester auxiliary in methanol containing a tertiary amine were found to give (S,S)- and (R,S)-3,4-dihydrobenzo[f]quinolinones (2) as major products. The magnitude of diastereomeric excess (de) for (S,S)-2 was varied from 0 to 55%, depending on the properties of the amine and solvent employed. The mechanism of asymmetric induction in the photocyclization process eventually affording 2 was discussed based on solvent, tertiary amine and temperature effects on the de value. (C) 2003 Elsevier Ltd. All rights reserved.