Lewis Acid Catalyzed Cascade Reactions of Diarylvinylidenecyclopropanes and 1,1,3‐Triarylprop‐2‐yn‐1‐ols or Their Methyl Ethers

Abstract

The reactions of vinylidenecyclopropanes 1 with 1,1,3-triarylprop-2-yn-1-ols or their methyl ethers 2 in the presence of a Lewis acid selectively produce 4-dihydro-1H-cyclopenta[b]naphthalene derivatives 3 or 1,2,3,8-tetrahydrocyclopenta[a]indene derivatives 4 depending on the substituents on the cyclopropane. Good to high yields are obtained under mild conditions. A plausible cascade Meyer-Schuster rearrangement and Friedel-Crafts reaction mechanism has been proposed. Moreover, novel functionalized methylenecyclobutene derivatives 5 could also be obtained in moderate to good yields under similar conditions when strongly electron-donating methoxy groups were introduced into the benzene rings of 2.

Iron(III)‐Catalyzed Cycloisomerizations of Acetal–Vinylidenecyclopropanes: An Efficient Synthetic Route to 1,2‐Disubstituted Cyclobutenes

“…In our previous work, we reported that the reaction of VDCPs with 1,1,3‐triarylprop‐2‐yn‐1‐ols or their methyl ethers selectively produced 4‐dihydro‐1 H ‐cyclopenta[ b ]naphthalene derivatives or 1,2,3,8‐tetrahydrocyclopenta[ a ]indene derivatives in the presence of Lewis acid, depending on the substituents at the cyclopropane 22. However, the intramolecular reaction of VDCPs with propargyl alcohol has not been explored to date.…”

“…Thus, the reactions of acetylb romide and FeBr 3 with other acetal-VDCPs 1 were then carriedo ut to define the Chem.E ur.J.2015, 21,15964 -15969 www.chemeurj.org generality of this protocol. Similarly,w hen using acetal-VDCPs 1b-j as the substrates, the desired brominated products 3b-j were obtained in moderate to good yields (50-68 %; Table 2, entries [14][15][16][17][18][19][20][21][22]. Next, the carbon chain length of acetal-VDCPs was extended and different acetals were synthesized to expand the substrate scope and conductf urthert ransformation of the products (Table 3).…”

“…In our previous work, we reportedt hat the reactiono f VDCPs with 1,1,3-triarylprop-2-yn-1-ols or their methyl ethers selectively produced 4-dihydro-1H-cyclopenta[b]naphthalene derivatives or 1,2,3,8-tetrahydrocyclopenta[a]indene derivatives in the presence of Lewis acid, depending on the substituents at the cyclopropane. [22] However,t he intramolecular reactiono f VDCPsw ith propargyl alcohol has not been explored to date. On the basis of the above investigation, we synthesized an ew propynol-VDCP 6 to investigate its reactivity in the presence of variousL ewis acids, and the resultsa re summarized in Supporting Information (Table S1).…”

“…Entry [a] x Solvent R y Yield [%] [b,c] generality of this protocol. Similarly,w hen using acetal-VDCPs 1b-j as the substrates, the desired brominated products 3b-j were obtained in moderate to good yields (50-68 %; Table 2, entries [14][15][16][17][18][19][20][21][22].…”