Efficient synthesis of 5,6,7-trisubstituted 1H-pyrrolizines
摘要:
Crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates and strong NH-acids, such as 2-pyrrolylglyoxalate or N-benzyl-2-pyrrolylglyoxamate. These phosphoranes undergo a smooth intramolecular Wittig reaction in boiling toluene to produce 5,6,7-trisubstituted 1H-pyrrolizine derivatives in quantitative yields. Dynamic NMR effects are observed in the H-1 NMR spectra of stabilized ylides 6a and 6d (DeltaG(not equal)=67.6 and 69.5 kJ mol(-1), respectively) and are attributed to restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group. (C) 2001 Elsevier Science Ltd. All rights reserved.
Copper-catalyzed oxidative cleavage of Passerini and Ugi adducts in basic medium yielding α-ketoamides
作者:Anirban Ghoshal、Mayur D. Ambule、Revoju Sravanthi、Mohit Taneja、Ajay Kumar Srivastava
DOI:10.1039/c9nj03533h
日期:——
oxidative cleavage of Passerini and Ugi adducts in the presence of base and copper(I) iodide is studied in detail. The oxidative cleavage yields α-ketoamides along with acids and amides from Passerini and Ugi adducts respectively. Mechanistic investigations revealed that the reaction proceeds via a radical pathway involving molecular oxygen. Control experiments with 18O-labeled Passerini adducts confirmed
Efficient synthesis of 5,6,7-trisubstituted 1H-pyrrolizines
作者:Issa Yavari、Mehdi Adib
DOI:10.1016/s0040-4020(01)00525-7
日期:2001.7
Crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates and strong NH-acids, such as 2-pyrrolylglyoxalate or N-benzyl-2-pyrrolylglyoxamate. These phosphoranes undergo a smooth intramolecular Wittig reaction in boiling toluene to produce 5,6,7-trisubstituted 1H-pyrrolizine derivatives in quantitative yields. Dynamic NMR effects are observed in the H-1 NMR spectra of stabilized ylides 6a and 6d (DeltaG(not equal)=67.6 and 69.5 kJ mol(-1), respectively) and are attributed to restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group. (C) 2001 Elsevier Science Ltd. All rights reserved.