Construction of cyclopenta[b]dihydronaphthofurans via TsOH-catalyzed consecutive biscyclization of dithioallylic alcohols and 1-styrylnaphthols

Abstract

An efficient TsOH-catalyzed consecutive biscyclization cascade reaction of dithioallylic alcohols with 1-styrylnaphthols is demonstrated for the concise construction of pharmaceutically important cyclopenta[b]dihydrobenzofurans scaffolds. This process involved an acid-catalyzed (3+2) cycloaddition...

Dithioallyl Cations in Stereoselective Dearomative (3 + 2) Cycloadditions of Benzofurans: Mechanism and Synthetic Applications

“…By using smaller amounts of acid, the general observation is that this will give an incomplete conversion and more side reactions as premature bimolecular deprotonation and quenching reactions occur. Very recently, He et al reported that highly nucleophilic styryl naphthol substrates only require a catalytic amount of para -toluenesulfonic acid to promote high-yielding reactions with dithioallyl alcohol 2 , but this effect is not observed for less reactive substrates.…”

“…Recently, our research group found that the dithioallyl alcohol 2 , wherein the alkene is fused to a 1,4-dithiane ring, , also serves as a simple and effective allyl cation precursor that undergoes a dearomative cycloaddition with various indoles (Scheme c) . Recently, He et al reported the use of the same dithioallyl alcohol to elaborate Cyclopenta[ b ]dihydrobenzofuran scaffolds in a cascade cyclization from 1-styryl-naphthols . Another logical extension of this work would be to probe the reactivity of benzofurans in such a reaction scheme (Scheme d).…”

“…16 Recently, He et al reported the use of the same dithioallyl alcohol to elaborate Cyclopenta-[b]dihydrobenzofuran scaffolds in a cascade cyclization from 1styryl-naphthols. 17 Another logical extension of this work would be to probe the reactivity of benzofurans in such a reaction scheme (Scheme 1d).…”

Sulfur in Waste‐Free Sustainable Synthesis: Advancing Carbon–Carbon Coupling Techniques

“…The most synthetically significant structural motifs in these transformations in recent years are ketene dithioacetals and 2,3-dihydro-1,4dithiines. [93][94][95] In addition to electrophilic substitution reactions, ketene dithioacetals are characterized by transformations catalyzed…”

Dithioallyl cation (3 + 2) cycloadditions under aprotic reaction conditions: rapid access to spiro-fused cyclopentane scaffolds

“…15 b Recently, He and Han reported an efficient (3 + 2) cycloaddition using dithio allyl alcohol 1 for the cyclopentannulation of styryl-naphthol substrates like 10 (Scheme 3d). 18 These specific substrates are indeed expected to be less prone to olefin oligomerization reactions, given their steric bulk, while they are also highly nucleophilic. These milder, catalytic procedures unfortunately do not give a good result for more generic intermolecular (3 + 2) olefin annulations, as they give low conversions and complex reaction mixtures.…”