Ring‐Expansion of MCPs in the Presence of DIAD or DEAD and Lewis Acids

Abstract

Keywords: Diethyl azodicarboxylate (DEAD) / Diisopropyl azodicarboxylate (DIAD) / Lewis acids / Ring expansion Treatment of methylenecyclopropanes (MCPs) with DIAD or DEAD in MeCN under mild conditions in the presence of Lewis acid Zr(OTf) 4 gave the cyclobutanone ring-expansion products in good to high yields based on the employed DIAD

Organoselenium‐Catalyzed Oxidative Ring Expansion of Methylenecyclopropanes with Hydrogen Peroxide

“…In 2004, Shi et al. reported the Lewis acid mediated ring expansion of MCPs with the use of either diisopropyl azodicarboxylate or diethyl azodicarboxylate . Later, Huang et al.…”

“…2‐(2‐Chlorophenyl)‐2‐phenylcyclobutanone ( 2 d ): Yield: 47.7 mg, 62 %; oil; IR (film): =1779, 1652, 1471, 1445, 755, 695 cm −1 ; 1 H NMR (400 MHz, CDCl 3 , Me 4 Si): δ =7.77–7.74 (m, 1 H), 7.36–7.18 (m, 8 H), 3.27–3.22 (m, 1 H), 3.18–3.12 (m, 2 H), 2.75–2.68 ppm (m, 1 H); 13 C NMR (100 MHz, CDCl 3 ): δ =207.6, 139.4, 137.9, 133.3, 131.2, 128.5, 128.4, 128.2, 126.9, 126.8, 126.5, 75.2, 43.0, 24.4 ppm; MS (EI, 70 eV): m / z (%): 221 (1) [ M + −Cl], 179 (100); known compound …”

Recent developments in the reactivity of methylene- and alkylidenecyclopropane derivatives

“…27 Indeed, these authors showed that alkylidenecyclopropanes with diisopropyl azodicarboxylate (DIAD) or diethyl azodicarboxylate (DEAD) in acetonitrile under mild conditions in the presence of Zr(OTf) 4 R 1 = R 2 = Ph, R 3 = Me: 55% R 1 = Ph, R 2 = H, R 3 = Me: 51% R 1 = p-BrC 6 H 4 , R 2 = H, R 3 = Me: 48% R 1 = R 2 = Ph, R 3 = Bn: 60% R 1 = R 2 = Ph, R 3 = n-Pr: 49% R 1 = p-BrC 6 H 4 , R 2 = H, R 3 = n-Pr: 53% underwent ring-expansion reactions to give the corresponding cyclobutanones in good-to-high yields (57e99%). The best results are collected in Scheme 16.…”

Lewis Acid‐Catalyzed Stereoselective [7+7] Intermolecular Cyclization of Aniline‐Tethered Alkylidenecyclopropanes: A One‐Step Synthetic Protocol of 14‐Membered Macrocyclic Dimers

“…Because the relief of ring strain can provide ap otent thermodynamic driving force, methylenecyclopropanes (MCPs) can undergo av ariety of ring-opening reactions under the catalysis of transition metals or Lewis acids. [5][6][7] In 2003, Yamamoto and co-workersr eported palladium-catalyzed intermolecular [3+ +2] cycloaddition of aniline-tethered alkylidenecyclopropanes to give the six-membered exo-methylene nitrogen heterocyclic products, [8] which showedthe availability of MCPs under transition-metal catalysis. Besides transition-metal catalysts, Lewis and Brønsted acids can also be used as catalysts or reagents in the reactions of MCPs with av ariety of substrates to produce new compounds, such as cyclobutanones, indenes, tetrahydrofurans, or tetrahydroquinolines.F or example, we have reported that MCPs could undergo [3+ +2] cycloaddition with N-tosyl iminest og ive the corresponding indene and pyrrolidine derivatives in the presenceo fB F 3 ·OEt 2 in moderate to good yields under mild conditions.…”