Base-catalyzed one-pot synthesis of dispiro-1,3-dioxolane bisoxindoles from N-methylisatin and methyl propiolate

Base-Catalyzed Reaction of Isatins and (3-Hydroxyprop-1-yn-1-yl)phosphonates as a Tool for the Synthesis of Spiro-1,3-dioxolane Oxindoles with Anticancer and Anti-Platelet Properties

An approach to the synthesis of phosphoryl substituted spiro-1,3-dioxolane oxindoles was developed from the base-catalyzed reaction of various isatins with (3-hydroxyprop-1-yn-1-yl)phosphonates. It was found that various aryl-substituted and N-functionalized isatins with the formation of appropriate products with high yields and stereoselectivity when using t-BuOLi are able to react. Cytotoxic activity evaluation suggests that the most significant results in relation to the HuTu 80 cell line were shown by N-benzylated spirodioxolanes. 5-Cloro-N-unsubstituted spirooxindoles exhibit antiaggregational activity exceeding the values of acetylsalicylic acid.

Diversity-oriented synthesis of benzofuro[3,2-b]pyridine derivatives from aurone-derived α,β-unsaturated imines and activated terminal alkynes

An efficient annulation reaction of aurone-derived α,β-unsaturated imines and activated terminal alkynes mediated by triethylamine is described, which enables the facile synthesis of 1,4-dihydrobenzofuro[3,2-b]pyridines in high yields. When the nucleophile of triethylamine was replaced with triphenylphosphine, another class of 1,4-dihydrobenzofuro[3,2-b]pyridines tethered with an additional acrylate motif were obtained instead. These two types of 1,4-dihydrobenzofuro[3,2-b]pyridines could be aromatized in the presence of DBU to afford benzofuro[3,2-b]pyridines, which could also be accessed via a one-pot procedure.

Synthesis of indolizines from pyridinium 1,4-zwitterionic thiolates and propiolic acid derivatives via a formal [4 + 1] pathway

Indolizines were synthesized from 1,4-zwitterionic thiolates and propiolic acid derivatives mediated by triethylamine via a formal [4 + 1] pathway.

Synthesis of 2-substituted 3-chlorobenzofurans via TMSCl-mediated nucleophilic annulation of isatin-derived propargylic alcohols

A TMSCl-mediated cascade annulation of isatin-derived propargylic alcohols for the synthesis of 2-substituted 3-chlorobenzofurans is now reported. Mechanistic investigations showed that this proceeded through a sequential Meyer-Schuster rearrangement/nucleophilic addition/intramolecular annulation. TMSCl not only acts as a promoter, but also acts as a chlorine source in this protocol.