SYNTHESIS OF CYCLOPROPA[C]COUMARINS FROM DONOR-ACCEPTOR CYCLOPROPANES

This work was supported by the Ministry of Education and Science of the Russian Federation (grant MK1567.2018.3)

Dimethyl 2-{[2-(2-Methoxy-1-methoxycarbonyl-2-oxoethyl)-4,5,7-trimethoxy-3-(2,4,5-trimethoxyphenyl)-2,3-dihydro-1H-inden-1-yl]methyl}malonate

A simple synthetic approach to dimethyl 2-{[2-(2-methoxy-1-methoxycarbonyl-2-oxoethyl)-4,5,7-trimethoxy-3-(2,4,5-trimethoxyphenyl)-2,3-dihydro-1H-inden-1-yl]methyl}malonate has been developed, based on a B(C6F5)3-induced domino dimerization of 2-(2,4,5-trimethoxyphenyl)cyclopropane-1,1-diester

Convenient Synthesis of Functionalized Cyclopropa[c]coumarin-1a-carboxylates

A simple method has been developed for the synthesis of cyclopropa[c]coumarins, which belong to the donor-acceptor cyclopropane family and, therefore, are promising substrates for the preparation of chromene-based fine chemicals. The method, based on the acetic acid-induced intramolecular transesterification of 2-arylcyclopropane-1,1-dicarboxylates, was found to be efficient for substrates containing hydroxy group directly attached to the aromatic ring

4b,5,6,9-Tetrahydro-7<i>H</i>-dibenzo[<i>c</i>,<i>e</i>]pyrrolo[1,2-<i>a</i>]azepin-7-one

A simple approach to synthesize 4b,5,6,9-tetrahydro-7H-dibenzo[c,e]pyrrolo[1,2-a]azepin- 7-one has been developed, based on a three-step transformation of 2-(2-bromophenyl)cyclopropane-1,1-diester. The key stage in this method is an intramolecular cross-coupling of 1-(2-bromobenzyl)-5-(2-bromophenyl)pyrrolidin-2-one under continuous flow conditions in an H-Сube-Pro using commercially available supported Pd catalysts

Synthesis of (Het)aryl 2-(2-hydroxyaryl)cyclopropyl Ketones

A simple general method for the synthesis of 1-acyl-2-(ortho-hydroxyaryl)cyclopropanes, which belong to the donor&ndash;acceptor cyclopropane family, has been developed. This method, based on the Corey&ndash;Chaykovsky cyclopropanation of 2-hydroxychalcones, allows for the preparation of a large diversity of hydroxy-substituted cyclopropanes, which can serve as promising building blocks for the synthesis of various bioactive compounds

Lewis Acid Triggered Vinylcyclopropane–Cyclopentene Rearrangement

We report a mild Lewis acid induced isomerization of donor–acceptor cyclopropanes, containing an alkenyl moiety and diverse electron-withdrawing group(s) at the adjacent positions, into substituted cyclopentenes. We have found that 1,1,2-trisubstituted cyclopent-3-enes were exclusively obtained in yield of 51–99% when cyclopropanes with a 2-substituted alkenyl group as a donor underwent isomerization. For cyclopropanes bearing a trisubstituted alkenyl group either the corresponding cyclopent-3-enes or isomeric cyclopent-2-enes having two acceptor groups at the C(1) atom were formed, with the reaction selectivity being determined by the applied Lewis acid. We have shown that the reactivity of the donor–acceptor cyclopropane increases with the increase of the electron-donating character of (hetero)­aromatic group attached to the alkenyl moiety. The synthetic utility of the developed methodology was also demonstrated through the synthesis of polysubstituted cyclopentane and piperidine derivatives

Lewis and Brønsted Acid Induced (3 + 2)-Annulation of Donor–Acceptor Cyclopropanes to Alkynes: Indene Assembly

(3 + 2)-Annulation of donor–acceptor cyclopropanes to alkynes induced by both Lewis and Brønsted acids has been developed. The reaction provides a rapid approach to functionalized indenes displaying intense visible emission (λ_max = 430 nm, Φ = 0.28–0.34)