Arylcyclopropanes synthesis

The carbenoid decomposition of an aryldiazomethane catalyzed by zinc halides in the presence of olefins is a convenient method for the synthesis of arylcyclopropanes 184). The reaction is syn-selective and yields are generally as good as or better than those obtained by previously... 

Scheme 24). A Li/SeMe exchange must be involved in the intermediate cycloal-kylmethyllithium to explain the cyclopropane ring formation. This lithium me-thaneselenolate displacement has been extended to the stereoselective synthesis of functionalized arylcyclopropanes by reaction with olefinic substrates [30] (Scheme 25). 

Cationic palladium-catalyzed addition of arylboronic acids to nitriles for the formation of benzo[h]furans was reported <06OL5987>, an example of which is illustrated in the following scheme. The palladium-catalyzed cross coupling of alkynes with appropriately substituted aryl iodides for the synthesis of substituted dibenzofurans in moderate to excellent yields was also achieved <06JOC5341>. The benzo[fc]furan core of heliannuls G and H were constructed by a palladium-catalyzed Ji-allyl cyclization reaction <06TL7353>. The palladium-catalyzed oxidative activation of arylcyclopropanes was applied to the synthesis of 2-substituted benzo[Z>]furans <06OL5829>. 

Hydroxyalkyl selenides derived from a-selenobenzyllithiums and epoxides have proved to be valuable precursors of arylcyclopropanes. The reaction proceeds through the corresponding 7-tosyloxy-benzyllithiums. Although the synthesis of the 7-hydroxyalkyl selenides is not stereoselective, the subsequent steps occur with high stereoselectivity, and have led to the conclusion that the benzyllithiums possess the opposite stereochemistry to that of the selenides and that this stereochemistry is retained in the next step (Scheme 18). ... 

Synthesis of arylcyclopropanes.4 Treatment of a benzyl chloride with LiTMP in ether generates a phenylcarbene or carbenoid species, which reacts with an olefin... 

Monoaryldiazomethanes, readily prepared by a number of methods, are the carbene precursors most frequently used for the synthesis of arylcyclopropanes. When such diazo compounds are decomposed photochemically, thermally, or by using various transition-metal salts in the presence of an alkene, arylcyclopropanes are formed. The yield is often quite high, but in a number of cases cyclopropane formation has been hampered by competing reactions, of which, disregarding intramolecular reactions, azine formation, stilbene formation, and hydrogen abstraction followed by dimerization are the most predominant. Many aspects related to the use of diazomethane derivatives as carbene precursors have been thoroughly discussed by Wentrup. ... 

Solladie-Cavallo, A., Diep-Vohuule, A. and Isarno, T. (1998) Two-step synthesis of trans-2-arylcyclopropane carboxylates with 98-lOOee by the use of a phosphazene base. Angewandte Chemie -Lntemational Edition, 37,1689-1691 Solladie-Cavallo, A., Roje, M., Isarno, T. etal. (2000) Pyridyl and furyl epoxides of more than 99% enantiomeric purities the use of a phosphazene base. European Journal of Organic Chemistry, 1077-1080 Solladie-Cavallo, A., Bouerat, L. and Roje, M. (2000) Asymmetric synthesis of trans-disubstituted aryl-vinyl epoxides a p-methoxy effect. Tetrahedron Letters, 41, 7309-7312. 

Gagnon A, Duplessis M, Fader L (2010) Arylcyclopropanes properties, synthesis and use in medicinal chemistry. Org Prep Proc Int 42 1-73... 

---