2-(1-Alkenyl)- and 2-aryl-substituted four-membered cyclic nitrones as precursors for 2,3,4-substituted pyridines and quinolines

Abstract

Reaction of the 2-(l-alkenyl)-substituted four-membered cyclic nitrones ether). 'H-NMR 6: 8.85 (d, in, J = 4.9 HZ, H-31, 8. 18 (d, lH, J = 4.9 Hz, H-4), 7.7-6.7 (m, 9H,

Unexpected one-pot synthesis of new polycyclic coumarin[4,3-c]pyridine derivatives via a tandem hetero-Diels–Alder and 1,3-dipolar cycloaddition reaction

“…e l s e v i e r . c o m / l o c a t e / t e t l e t now, the synthesis of these compounds 19 had been realized via procedures, often multistep, utilizing as precursors, substituted four-membered 2-aryl-cyclic nitrones, 20 o-cyanocarbonyl-coumarin derivatives, 21 and suitably substituted oxopiperidinecarboxylates, 8 aryl-4-picolines, 22 quinolinones, 23 and quinolines. 24 To the best of our knowledge, the application of HDA reactions on the coumarin nucleus is limited.…”

Regioselective Transformation of O-Propargylic Arylaldoximes to Four-Membered Cyclic Nitrones by Copper-Catalyzed Skeletal Rearrangement

“…However, there was an obvious drawback in the regioselectivity, when 1 has different substituents at the propargylic position and the oxime moiety (R 2 ≠ R 3 ) (eq ). Herein, we report on the copper-catalyzed skeletal rearrangement of ( E )- 1 that produced 2 with excellent regioselectivities by using [CuCl(cod)] 2 as catalysts under mild reaction conditions (eq ) . Moreover, mechanistic studies revealed that the present reaction proceeds via a tandem [2,3]-rearrangement and 4π-electrocyclization. …”

Rhodium-Catalyzed [2 + 2] Cycloaddition of Ynamides with Nitroalkenes

“…The closest precedent to this process is the work of the Reinhoudt group describing the uncatalyzed reactions of ynamines with nitroalkenes which, in addition to cyclobutenamines, gave, in most cases, four-membered cyclic nitrones (representative example in eq ) …”