N-Heterocyclic carbene-catalyzed diastereoselective synthesis of sulfenylated indanesviasulfa-Michael–Michael (aldol) cascade reactions

Abstract

N-Heterocyclic carbene (NHC)-catalyzed diastereoselective synthesis of multisubstituted sulfenylated indanes has been developed.

Triflic Acid-Catalyzed Synthesis of Indole-Substituted Indane Derivatives via In Situ Formed Acetal-Facilitated Nucleophilic Addition and 4π-Electron-5-Carbon Electrocyclization Sequence

“…Notably, Crixivan, developed by Merck, is an HIV protease inhibitor used as an important drug for the treatment of AIDS, and resveratrol-derived natural products such as caraphenols, α-diisoeugenol, and endothelin receptor antagonist SB 209670 are a few other biologically important compounds to mention (Figure ). Owing to their widespread natural and biological relevance, the indane scaffold attracted researchers to pursue its chemical synthesis, and different protocols have been reported in literature for the synthesis of indane derivatives in both racemic and asymmetric manners. − …”

Metal-free thioesterification of α,β-unsaturated aldehydes with thiols

“…1 H NMR and 13 C NMR spectra were recorded in CDCl 3 on a Varian 400 operated at 402.6 and 101.2 MHz, respectively. 19 F NMR spectra were recorded in CDCl 3 on a Varian Mercury 300 operated at 282.6 MHz. HMBC spectra were recorded on a Bruker Avance DRX 600, operated at a frequency of 600.13 MHz ( 1 H).…”

“…[12][13][14] Although they usually give high product yields, these methods still suffer from a number of drawbacks, such as the need for high temperature, long reaction time and inevitability of oxidant use. These routes are also limited to aryl and alkyl aldehydes and cannot be applied for α,β-unsaturated compounds because these types of aldehydes react with thiols in the presence of NHC to give SMA adducts [15][16][17][18][19] (Scheme 1c). According to the best of our knowledge, there is only one report on the synthesis of thioethers via β-protonation of α,β-unsaturated enals using mercaptans 20 (Scheme 1d).…”

N-Heterocyclic Carbene-Mediated Carbon–Sulfur Bond-Forming Reactions

“…In 2019, the same group disclosed an efficient method for the synthesis of sulfenylated indan 136 via a carbene-catalyzed S-Michael–Michael cascade reaction between thiol 131 and benzenedienone 135 (Figure ). This reaction requires only 1 mol % of a free carbene catalyst to promote the formation of sulfinated indanes with good to excellent yields and diastereoselectivities.…”