1-(Triethoxysilyl)buta-1,3-dienes-New Building Blocks for Stereoselective Synthesis of Unsymmetrical (E,E)-1,4-Disubstituted 1,3-dienes

Base-promoted direct E-selective olefination of organoammonium salts with sulfones toward stilbenes and conjugated 1,3-dienes

A base-promoted direct deaminative olefination of organoammonium salts was developed. Only mediated by KO^tBu, a series of benzyl and cinnamyl ammonium salts reacted smoothly with sulfones, producing the valuable stilbenes and related 1,3-diene derivatives in good to high yields with good functional group tolerance and excellent E-selectivity. With this developed method, biologically active resveratrol and DMU-212 were also successfully prepared, which further demonstrates the practicality of this reaction.

Readily available alkylbenzenes as precursors for one-pot preparation of buta-1,3-dienes under DDQ visible-light photocatalysis in benzotrifluoride

Easily accessible alkylbenzenes are highly valuable starting materials and solvents in synthetic organic chemistry for production of pharmaceuticals, plastics, synthetic rubber, dyes, etc. Herein, by employing alkylbenzenes as precursors, an...

Oxidative homodimerization of substituted olefins by DDQ visible light photocatalysis

A metal-free approach for the synthesis of buta-1,3-dienes from olefins using visible-light and catalytic amounts of DDQ is disclosed.

One-step preparation of novel 1-(N-indolyl)-1,3-butadienes by base-catalysed isomerization of alkynes as an access to 5-(N-indolyl)-naphthoquinones

A series of novel 1-(N-indolyl)-1,3-butadienes, as (1 : 1) mixtures of the (E) and (Z) dienes, was prepared in one step by base-catalysed isomerization of N-alkylindoles with a terminal butyne chain. The reaction conditions are mild, and in all cases the yields were very high (>90%). The (E) and (Z) dienes were separable by preparative TLC and could be fully characterized. This isomerization proceeded readily in the case of a butynyl chain, but didn't take place with a pentynyl chain. A mechanism was proposed for this reaction, based on previous studies on the isomerization of alkynes in basic media, and a key intermediate that supports the proposed mechanism could be isolated and fully characterized. A theoretical study of the proposed mechanism was performed by computational methods and the results validated the proposal. The reactivity of the synthesized dienes was studied in Diels–Alder reactions with p-benzoquinone, to obtain a small library of new 5-(N-indolyl)-1,4-naphthoquinones.The lack of reactivity in the case of the (Z) isomers was explained by calculation of the rotational curves of the central bond of the (Z) and (E) dienes. Finally, the cytotoxicity of the new 5-(N-indolyl)-1,4-naphthoquinones was tested against a panel of three cell lines.

A series of novel 1-(N-indolyl)-1,3-butadienes, was easily prepared in one step and used for the synthesis of 5-(N-indolyl) naphthoquinones.