Diastereoselective intramolecular hetero Diels–Alder approach towards polycyclic heterocycles
作者:Erik Ceulemans、Marieke Voets、Sabine Emmers、Koen Uytterhoeven、Luc Van Meervelt、Wim Dehaen
DOI:10.1016/s0040-4020(01)01153-x
日期:2002.1
Several different heterocyclic aldehydes, derived from pyrazole. pyrimidine, pyridine, indole and thiazole, were converted to polyheterocyclic compounds containing four to seven rings. The key steps in the sequence were a Knoevenagel condensation of the aldehyde and a heterocyclic carbonyl compound, such as pyrazolone and isoxazolone, followed by an intramolecular hetero Diets-Alder reaction. Most final products were isolated with high yield and diastereoselecivity. The isoxazolo fused cycloadducts formed interesting spiro-adducts upon heating. The cis nature of the bridging hydrogens of the heterocycles was evidenced by X-ray diffraction analysis.(dagger) (C) 2002 Elsevier Science Ltd. All rights reserved.
On-Demand Selection of the Reaction Path from Imino Diels-Alder to Ene-Type Cyclization: Synthesis of Epiminopyrimido[4,5-<i>b</i>]azepines
作者:Yuewei Zhang、Yue Zhu、Lianyou Zheng、Lian-Gang Zhuo、Fengzhi Yang、Qun Dang、Zhi-Xiang Yu、Xu Bai
DOI:10.1002/ejoc.201301318
日期:2014.1
selection of the final products from the same starting materials. The successful execution of such a strategy will reduce the time required to prepare diverse scaffolds. The imines derivedfrom 4-(allylamino)pyrimidine-5-carbaldehydes and anilines undergo Diels–Alder reactions to give pyrimido[4,5-h][1,6]naphthyridines in high yields. A complete switch from the intramolecular aza-Diels–Alder (IADA) path