Abstract Acetyl-substituted heterocyclic enamines 4 were synthesized from lactim ethers 2 and acetylacetone through condensation and deacetylation reactions, and they, along with the ester-substituted heterocyclic enamines 6, reacted with diethylazodicarboxylate to afford C-adducts 7 and 8 in excellent yields.
Cyclic beta-enaminones bearing secondary amino group react with 4-substituted benzenediazonium tetraphenylborates in dichloromethane to form substituted bicyclic [1,3,2 lambda(4)] oxazaborines The oxazaborines rearrange, on heating to 200 degrees C in the absence of solvent or in DMF or DMSO, to isomeric 2H-[1,2,4,3 lambda(4)] triazaborines. Previously prepared [1,3,2 lambda(4)] oxazaborines derived from acyclic beta-enaminones bearing secondary amino group either did not undergo the rearrangement or with a lot of difficulties and with negligible yield. The fluorescence behaviour of the prepared triazaborines was observed. These compounds fluoresce in 2-methyltetrahydrofurane and in solid state under low temperatures. (C) 2011 Elsevier B.V. All rights reserved.
Synthesis of [1,2-a]-fused tricyclic dihydroquinolines by palladium-catalyzed intramolecular C–N cross-coupling of polarized heterocyclic enamines
作者:Břetislav Brož、Zdeňka Růžičková、Petr Šimůnek
DOI:10.3998/ark.5550190.p009.723
日期:——
A simple methodology for [1,2-a]-fusedtricyclicdihydroquinolines is established. The key step of the methodology is an intramolecular Buchwald-Hartwig amination reaction of suitable halogenated (both bromo and chloro) cyclic enaminoketones, enaminoesters and enaminonitriles with various ring size (from fiveto seven-membered). Optimal reaction conditions (palladium source, base, ligand) depend on