Iodine-Mediated Diastereoselective Cyclopropanation of Arylidene Malononotriles by 2,6-Dimethylquinoline

Abstract

A novel iodine-mediated reaction of 2,6-dimethylquinoline with Knoevenagel condensation products of malononitrile with benzaldehydes, leading to a facile, one-pot synthesis of 2-aryl-3-(6-methylquinolin-2-yl)cyclopropane-1,1-dicarbonitriles, in moderate to good yields, is described.

Diastereoselective Synthesis of Spirocyclopropane‐Linked Pyrazolones from Azomethine Ylides via C(sp3)‐H Activation

“…In all products, rac‐anti‐5 a‐e and rac‐syn‐5 a‐e , the coupling constant between the two vicinal cyclopropyl protons ( 3 J =7.5–9.5 Hz) confirm a trans configuration. In trans‐cyclopropane derivatives, the vicinal coupling constant of the two methine protons is about 3 J =2‐5 Hz, while in cis‐cyclopropanes the vicinal coupling constant 3 J =6‐12 Hz ,. From the X‐ray structure shown in Figure , it can be seen that the quinolinyl and phenyl groups are anti.…”

“…On the other hand, the quinolinyl and carbonyl group of pyrazolone moiety exist in trans‐position, so we call this isomer rac‐anti‐5 a . According to 1 H NMR data and comparison with the earlier reported results, we conclude that the two substituents at 2,3‐positions of cyclopropyl ring of products 5 , have trans‐arrangement. This result clearly indicate that the Michael‐initiated cyclopropanation of pyridinium ylides is a diastereoselective reaction.…”

Metal‐Free Cross‐Dehydrogenative Coupling (CDC): Molecular Iodine as a Versatile Catalyst/Reagent for CDC Reactions

“…The diastereoselective cyclopropanation of arylidine malononitriles by 2,6-dimethylquinoline throughb enzylic CÀHf unc- tionalization has been reported (Scheme21). [33] Arylidine malononitriles with electron-donatingo re lectron-withdrawing groups have successfully been employedu nder the reaction conditions to furnish the products in moderate to good yields. I 2 activatesq uinolone 75 by coordination with the nitrogen atom;s ubsequent elimination of HI functionalizes the benzylic C(sp 3 )ÀHb ond of 76 to form 77.N ucleophilic attack of pyridine on 77 leads to the formation of 78,w hich is converted into nitrogen ylide 79 by diisopropylethylamine (DIPEA).Y lide 79 then attacks arylidine malononitrile 80 to give reactive species 81,which rapidly undergoes cyclization to form cyclopropyl derivative 83 with the elimination of pyridine.…”

“…The diastereoselective cyclopropanation of arylidine malononitriles by 2,6‐dimethylquinoline through benzylic C−H functionalization has been reported (Scheme ) . Arylidine malononitriles with electron‐donating or electron‐withdrawing groups have successfully been employed under the reaction conditions to furnish the products in moderate to good yields.…”

FeCl3-catalyzed formation of indolizine derivatives via the 1,3-dipolar cycloaddition reaction between azomethine ylides and chalcones or dibenzylideneacetones

“…9 Recently, we reported a one-pot protocol that combined the in-situ formation of an azomethine ylide and its subsequent reaction with electron-poor arylidene-malononitriles to give cyclopropane products. 10 In the present paper, we applied this methodology to more electron-rich olefins, such as chalcones and dibenzylideneacetone derivatives in the presence of FeCl 3 , where the major reaction is not cyclopropane formation, but a 1,3-dipolar cycloaddition. This is likely due to the reactivity/stability of the anionic intermediate generated after the addition of the azomethine ylide to the dienophile.…”