Electron Transfer-initiated Photocyclization of Substituted a-Dehydro(1-naphthyl)alanines
摘要:
On irradiation in the presence of triethylamine, the title compounds (1) having n-butyl and benzyl groups gave preferentially dihydrobenzoquinolinones (2) via electron transfer, whereas the introduction of the bulky tert-butyl and phenyl substituents into 1 resulted in the formation of benzoisoquinoline (3) and 1-azetine (4) derivatives without affording 2.
Electron Transfer-initiated Photocyclization of Substituted a-Dehydro(1-naphthyl)alanines
摘要:
On irradiation in the presence of triethylamine, the title compounds (1) having n-butyl and benzyl groups gave preferentially dihydrobenzoquinolinones (2) via electron transfer, whereas the introduction of the bulky tert-butyl and phenyl substituents into 1 resulted in the formation of benzoisoquinoline (3) and 1-azetine (4) derivatives without affording 2.
Electron transfer-initiated photocyclization of substituted N-acetyl-α-dehydro(1-naphthyl)alanines to 1,2-dihydrobenzo[f]quinolinone derivatives: scope and limitations
The irradiation of substituted N-acetyl-alpha -dehydro(1-naphthyl)alanines (1) in MeOH containing triethylamine with Pyrex-filtered light gave 1,2-dihydrobenzo[f]quinolinones (2) in preference to benzo[f]isoquinolines (3) and 1-azetines (4). Analysis of substituent effects on the product compositions revealed that the selectivity of 2 has a strong tendency to decrease with increasing steric bulkiness of the alkyl substituent introduced into the starting (Z)-1. From control and fluorescence quenching experiments it was shown that the photocyclization reaction of 1 affording 2 proceeds by an electron-transfer mechanism. The mechanism of this novel cyclization was discussed mainly based on substituent and solvent effects on both the reactivities of the excited singlet-state 1 and the selectivities of the products 2-4. (C) 2001 Elsevier Science Ltd. All rights reserved.