Synthesis and isomerization of N-α-aza-heteroaryl-β-lactams
摘要:
The [2+2] carbonylative cycloaddition of N-cx-aza-heteroaryl substituted imines with allyl bromide led partially to beta-lactams, which underwent isomerization to the more stable alpha,beta-unsaturated carbonyl compound. Pyrimidinone derivatives together with doubly unsaturated amides represent the remaining isolated products. The strong electron-withdrawing effect of the two alpha-aza-heterocycles linked to the nitrogen atom and to the C4 of the 2-azetidinone structure could give a ring expansion, through a 2-azetinone intermediate that affords the pyrimidinone compounds. The substituted amides, instead, should result from a ring-opening reaction of the beta-lactam. (c) 2006 Elsevier Ltd. All rights reserved.
The [2+2] carbonylative cycloaddition of N-cx-aza-heteroaryl substituted imines with allyl bromide led partially to beta-lactams, which underwent isomerization to the more stable alpha,beta-unsaturated carbonyl compound. Pyrimidinone derivatives together with doubly unsaturated amides represent the remaining isolated products. The strong electron-withdrawing effect of the two alpha-aza-heterocycles linked to the nitrogen atom and to the C4 of the 2-azetidinone structure could give a ring expansion, through a 2-azetinone intermediate that affords the pyrimidinone compounds. The substituted amides, instead, should result from a ring-opening reaction of the beta-lactam. (c) 2006 Elsevier Ltd. All rights reserved.
Tandem-Selective Bond Cleavage of the Lactam Nucleus and Michael Reaction
作者:Luisella De Vitis、Luigino Troisi、Catia Granito、Emanuela Pindinelli、Ludovico Ronzini
DOI:10.1002/ejoc.200600597
日期:2007.1
The reactivity of the β-lactam ring towards nucleophiles has been investigated. Ring-opening reactions were performed on 3-allyl-β-lactams with CH3O–/CH3OH at room temperature and/or reflux. Lactamnucleus isomerization followed by N1–C2 bondcleavage and methanol Michael addition afforded substituted amino esters. The reactivity of the four-membered ring towards nucleophiles was found to depend on