Reductive Denitrogenation of Six-membered Cyclic Nitronates to Densely Substituted Dihydrofurans with Raney ® Nickel/AcOH System Evgeny V. Pospelov, a Alexander V. Zhirov, a, b Baglan Kamidolla, a, c and Alexey Yu. Sukhorukov a, * a N. D. Zelinsky Institute of Organic Chemistry, 119991, Leninsky prospect, 47, Moscow, Russia E-mail: sukhorukov@ioc.ac.ru; a.yu.sukhorukov@gmail.com b Department of Chemistry, M.V. Lomonosov Moscow State University, 119991, Leninskie gory, 1, str. 3, Moscow, Russia c D. Mendeleev University of Chemical Technology of Russia, 125047, Miusskaya sq., 9, Moscow, Russia Manuscript received: May 30, 2023; Revised manuscript received: July 12, 2023; Version of record online: August 1, 2023 Supporting information for this article is available on the WWW under https://doi.org/10.1002/adsc.202300573 Abstract: A protocol for the synthesis of 2,3- dihydrofurans by reductive denitrogenation/ring contraction of 6-membered cyclic nitronates was developed. The process utilizes cheap Raney ® nickel both as catalyst and stoichiometric agent without the need for high-pressure equipment. The products are formed in high purity and column chromatography is often not required. Studies on the substrate scope, functional group tolerance, and mechanism were performed. The developed approach provides a straightforward two-step access to densely substi- tuted 2,3-dihydrofurans from nitrostyrenes and alkenes. Keywords: Dihydrofurans; Denitrogenation; Ring contraction; Heterogeneous catalysis; Nitronates 2,3-Dihydrofuran is an important five-membered het- erocycle that is present in many natural compounds and active pharmaceutical ingredients. Representative examples include anti-inflammatory drug Polmacoxib (Acelex ® ), [1] herbicide (R)-flurtamone, [2] and Austocys- tin D, a natural compound with potent cytotoxic activity (Scheme 1, a). [3] 2,3-Dihydrofurans serve as key intermediates in organic synthesis as reactive π- nucleophiles, dipolarophiles, dienophiles in the in- verse-electron demand Diels-Alder reaction, and surro- gates of γ-hydroxycarbonyl compounds in heterocycli- zation reactions. [4] Apart from this, simple 2,3- dihydrofurans were recently shown to be useful monomers for production of degradable thermoplastic elastomers. [5] Though numerous methods to assemble Scheme 1. Background of the study. COMMUNICATIONS doi.org/10.1002/adsc.202300573 Adv. Synth. Catal. 2023, 365, 2850 – 2857 © 2023 Wiley-VCH GmbH 2850