1,3-Dipolar cycloaddition of nitrones to oxa(aza)bicyclic alkenes

Abstract

A new 1,3-dipolar cycloaddition of oxa(aza)bicyclic alkenes with nitrones has been developed without any catalyst and additive under mild conditions. The proposed concerted mechanism is investigated by DFT calculations of the reaction pathways.

Cobalt(II)‐Catalyzed [4+2] Annulation of Picolinamides with Alkynes via C−H Bond Activation

“…Furthermore, the reactions were treated with radical trapping reagents butylated hydroxytoluene (BHT) and 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) under the optimized reaction conditions in parallel. As a result, both BHT and TEMPO had no inhibitory effects on the reactions, which indicating that the radical process should not involve in the alkenylation reaction (Scheme b) . In addition, the Co II ‐catalyzed annulation reaction of picolinamide 1 a and 1,4‐diphenylbutadiyne 4 was performed under the standard reaction conditions, no desired annulation product 3 aa was formed (Scheme c).…”

Catalyst‐Free Regioselective [3+2] Cycloadditions of α,β‐unsaturated N‐arylnitrones with Alkenes to Access Functionalized Isoxazolidines: A DFT Study

“…al. 20 reported, catalystfree cycloaddition of oxa(aza)bicyclic alkenes with nitrones as the 1,3-dipolar cycloaddition under mild conditions, which can afford the new products of fused bicyclic tetrahydroisoxazoles (Scheme 1c). The reactions occur diastereoselectively, with a notable exo-and anti-preference and thus, observed diastereoselectivity trends as predicted by DFT calculations.…”

Negligible Substituent Effect as Key to Synthetic Versatility: a Computational‐Experimental Study of Vinyl Ethers Addition to Nitrile Oxides

“…Concerted 1,3-dipolar cycloadditions are often studied with computational modeling. [5,7,[11][12][13][54][55][56][57][58] The cycloadditions to nitrile oxides of substituted alkenes and alkynes are no exception. [11,13,59,60] Most noticeable computational studies address regioselectivity of 1,3-dipolar cycloadditions.…”

“…Concerted 1,3‐dipolar cycloadditions are often studied with computational modeling [5,7,11–13,54–58] . The cycloadditions to nitrile oxides of substituted alkenes and alkynes are no exception [11,13,59,60] .…”