(4+3) Cycloaddition Reactions of N‐Alkyl Oxidopyridinium Ions. Issue 46 (16th October 2017)

• Record Type: Journal Article
• Authors: Fu, Chencheng; Lora, Nestor; Kirchhoefer, Patrick L.; Lee, Dong Reyoul; Altenhofer, Erich; Barnes, Charles L.; Hungerford, Natasha L.; Krenske, Elizabeth H.; Harmata, Michael
• Is Part Of: Angewandte Chemie international edition. Volume 56:Issue 46(2017)
• Page Start: 14682
• Page End: 14687
• Publication Date: 2017-10-16
• Subjects: alkaloids -- (4+3) cycloaddition -- dienes -- pyridinium ions; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201708320
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: N ‐Methylation of methyl 5‐hydroxynicotinate followed by reaction with a diene in the presence of triethylamine afforded (4+3) cycloadducts in good to excellent yields. High regioselectivity was observed with 1‐substituted and 1, 2‐disubstituted butadienes. Density functional theory calculations indicate that the cycloaddition involves concerted addition of the diene onto the oxidopyridinium ion. The process provides rapid access to bicyclic nitrogenous structures resembling natural alkaloids. Abstract : Greater than the sum of its parts : N‐Methylated methyl 5‐hydroxynicotinate reacted with dienes in the presence of triethylamine to afford bicyclic nitrogenous structures resembling natural alkaloids through (4+3) cycloaddition (see scheme). High regioselectivity was observed with 1‐substituted and 1, 2‐disubstituted butadienes. DFT calculations indicate that the reaction involves concerted addition of the diene to the oxidopyridinium ion.