Thanks to the ability of diazo derivatives to react either as 1,3-dipoles and as carbenes after dinitrogen extrusion, combinations of oxa or aza benzonorbornadienes and diazomalonates afford polycyclic pyrazolidines via a three-step sequence of (i) a highly diastereoselective [3+2]-cycloaddition, (ii) a CpRu-catalyzed carbene addition, and (iii) a second dipolar cycloaddition. Of importance, step (II) represents a unique access to novel bench-stable N,N-cyclic azomethine imines, which behave as effective 1,3-dipoles in combination with electron-poor dipolarophiles. Each step proceeds efficiently and the 3-step process can be performed in one-pot to yield a polycyclic pyrazolidine in excellent overall yield (90 %).
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http://dx.doi.org/10.1002/chem.202401522 | DOI Listing |
Molecules
October 2024
School of Preclinical Medicine, Zunyi Medical University, Zunyi 563006, China.
The metathesis reaction between carbonyl compounds and olefins has emerged as a potent strategy for facilitating swift functional group interconversion and the construction of intricate organic structures through the creation of novel carbon-carbon double bonds. To date, significant progress has been made in carbonyl-olefin metathesis reactions, where oxetane, pyrazolidine, 1,3-diol, and metal alkylidene have been proved to be key intermediates. Recently, several reviews have been disclosed, focusing on distinct catalytic approaches for achieving carbonyl-olefin metathesis.
View Article and Find Full Text PDFChemistry
August 2024
Department of Organic Chemistry, University of Geneva, Quai Ernest Ansermet 30, 1211, Geneva 4, Switzerland.
Thanks to the ability of diazo derivatives to react either as 1,3-dipoles and as carbenes after dinitrogen extrusion, combinations of oxa or aza benzonorbornadienes and diazomalonates afford polycyclic pyrazolidines via a three-step sequence of (i) a highly diastereoselective [3+2]-cycloaddition, (ii) a CpRu-catalyzed carbene addition, and (iii) a second dipolar cycloaddition. Of importance, step (II) represents a unique access to novel bench-stable N,N-cyclic azomethine imines, which behave as effective 1,3-dipoles in combination with electron-poor dipolarophiles. Each step proceeds efficiently and the 3-step process can be performed in one-pot to yield a polycyclic pyrazolidine in excellent overall yield (90 %).
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