One-pot cyclization of dilithiated nitriles with isothiocyanates and epibromohydrin. Synthesis of 2-cyano-1-(hydroxymethyl)cyclopropanes and 2-cyanomethylidene-4-(hydroxymethyl)thiazolidines

The cyclization of dilithiated nitriles with epibromohydrin afforded 2-cyano-1-(hydroxymethyl)cyclopropanes. 2-Cyanomethylidene-(4-hydroxymethyl)thiazolidines were prepared by one-pot cyclization of dilithiated nitriles with isothiocyanates and epibromohydrin.     

Synthesis of 1,4-diaza-7-oxabicyclo[4.3.0]non-2-en-6-ones by cyclization of 1,1-bis(trimethylsiloxy)ketene acetals with pyrazine and quinoxaline

1,4-Diaza-7-oxabicyclo[4.3.0]non-2-en-6-ones were prepared by cyclization of 1,1-bis(trimethylsiloxy)ketene acetals with pyrazine and quinoxaline.     

Synthesis and reactions of hydroxyspiro[5.2]cyclooctenones based on the cyclization of the dianions of acetone and diethyl 2-oxopropylphosphonate with 1,1-diacylcyclopropanes

The cyclization of the dianions of diethyl 2-oxopropylphosphonate and of acetone with 1,1-diacylopropanes afforded hydroxyspiro[5.2]cyclooctenones which were transformed, by homo-Michael reactions with tetrabutylammonium halides, into various functionalized phenols or their dimers.     

Synthesis of 6-alkylidene-2,3-benzo-1,4-diaza-7-oxabicyclo[4.3.0]non-2-enes by cyclization of 1,3-bis(silyl enol ethers) with quinoxalines

6-Alkylidene-2,3-benzo-1,4-diaza-7-oxabicyclo[4.3.0]non-2-enes were prepared by cyclization of 1,3-bis(silyl enol ethers) with quinoxaline.     

One-pot synthesis of 3-hydroxymaleic anhydrides by cyclization of 1,1-bis(trimethylsilyloxy)ketene acetals with oxalyl chloride

Functionalized 3-hydroxymaleic anhydrides were prepared by cyclization of 1,1-bis(trimethylsilyloxy)ketene acetals with oxalyl chloride.     

Regioselective synthesis of functionalized 2-(phenylthio)benzoates by ‘[3+3] cyclization/homo-Michael’ reactions of 1-methoxy-1-trimethylsilyloxy-3-phenylthio-1,3-butadienes with 1,1-diacylcyclopropanes

2-(Phenylthio)benzoates containing a remote halide function are regioselectively prepared by ‘[3+3] cyclization/homo-Michael’ reactions of 1-methoxy-1-trimethylsilyloxy-3-phenylthio-1,3-butadienes with 1,1-diacylcyclopropanes.     

Synthesis of 7,8-benzo-9-aza-4-oxabicyclo[3.3.1]nonan-3-ones by sequential ‘condensation–iodolactonization’ reactions of 1,1-bis(trimethylsilyloxy)ketene acetals with isoquinolines

Functionalized 7,8-benzo-9-aza-4-oxabicyclo[3.3.1]nonan-3-ones were prepared by regio- and diastereoselective condensation of 1,1-bis(silyloxy)ketene acetals with isoquinolinium salts and subsequent regioselective and stereospecific iodolactonization.     

Synthesis of isotetronic acids by cyclization of 1,3-bis(trimethylsilyloxy)alk-1-enes with oxalyl chloride

Isotetronic acids were regioselectively prepared by cyclization of 1,3-bis(trimethylsilyloxy)alk-1-enes with oxalyl chloride.     

Synthesis of 1-sulfonyl-2-arylpyrrolidines via intramolecular cyclization/Mannich-type reaction cascade of N-(4,4-diethoxybutyl)sulfonamides

Abstract

Herein, we report the successful application of a novel approach to 2-substituted pyrrolidines based on intramolecular cyclization/intermolecular Mannich-type cascade reaction of N-(4,4-diethoxybutyl)sulfonamides to the synthesis of pyrrolidines possessing heterocyclic and polyaromatic moieties. The proposed approach benefits from mild reaction conditions, moderate to high yields of target compounds and provides a convenient route to the previously unknown 1-sulfonyl-2-arylpyrrolidines.     

Synthesis of functionalized 2-(arylthio)benzoates by formal [3+3] cyclizations of 3-arylthio-1-silyloxy-1,3-butadienes with 3-silyloxy-2-en-1-ones and 1,3-diacylcyclopropanes

Functionalized 2-(arylthio)benzoates are prepared by formal [3+3] cyclizations of 3-arylthio-1-trimethylsilyloxy-1,3-butadienes with 3-silyloxy-2-en-1-ones and 1,1-diacylcyclopropanes.     

Synthesis of 7-arylquinolinones and 6-arylindoles from 3-aminobiphenyls through regioselective cyclization reactions

7-Arylquinolinones were obtained in two steps from 3-aminobiphenyls through conversion into cinnamic amides. The highly regioselective cyclization under elimination of anisole proceeded in the presence of phosphoric acid and phosphorous pentoxide. 6-Arylindoles were accessible, although in lower yields, from 3-aminobiphenyls via 3-(biphenylamino)acrylates and palladium-catalyzed cyclization reactions.     

Synthesis of 6-(perfluoroalkyl)salicylates by [3+3] cyclization of 1,3-bis(silyl enol ethers) with 3-ethoxy-1-(perfluoroalkyl)prop-2-en-1-ones

6-(Perfluoroalkyl)salicylates were prepared by [3+3] cyclization of 1,3-bis(silyl enol ethers) with 3-ethoxy-1-(perfluoroalkyl)prop-2-en-1-ones.     

Synthesis of sterically encumbered and functionalized diaryl-diazenes by formal [3+3] cyclization of 2-aryldiazenyl-3-silyloxy-2-en-1-ones with 1,3-bis(silyloxy)-1,3-butadienes

Functionalized diaryl-diazenes (azo-dyes) were regioselectively prepared by formal [3+3] cyclization of 1,3-bis(silyloxy)-1,3-butadienes with 2-aryldiazenyl-3-silyloxy-2-en-1-ones.     

Synthesis of 3-(quinoxalin-2-yl)-2H-chromen-2-ones under microwave irradiation

Abstract  A facile procedure for the synthesis of quinoxalines is being reported starting from 3-(2-bromoacetyl)coumarins or 3-(2-bromobutanoyl)coumarins and substituted o-phenylenediamines. The reactions were carried out under catalyst-free and microwave irradiation conditions producing the title compounds in moderate to excellent yields in a short time with easy workup. The structures of all new compounds have been confirmed on the basis of their IR, ¹H NMR, ¹³C NMR, and HRMS data. Graphical Abstract        

Synthesis of 5-(2-aryl-2-haloethyl)salicylates by the first domino ‘[3+3] cyclization/ring-cleavage’ reactions of 1,3-bis(silyloxy)-1,3-butadienes with 3-acetyl-5-aryl-4,5-dihydrofurans

5-(2-Aryl-2-haloethyl)salicylates are efficiently prepared by the first domino ‘[3+3] cyclization/ring-cleavage’ reactions of 1,3-bis(silyloxy)-1,3-butadienes with 3-acetyl-5-aryl-4,5-dihydrofurans.     

Synthesis of 2,5-dihydrobenzo[b]oxepins and 5,6-dihydro-2H-benzo[b]oxocines based on [3+3] cyclizations of 1,3-bis(silyl enol ethers)

Functionalized 2,5-dihydrobenzo[b]oxepins and 5,6-dihydro-2H-benzo[b]oxocines were prepared based on a ‘[3+3] cyclization-olefin-metathesis’ strategy.     

Synthesis and reactions of 2-chloro-1,3-bis(trimethylsilyloxy)-1,3-butadienes

The reaction of 2-chloro-1,3-bis(trimethylsilyloxy)-1,3-butadienes with various electrophiles allows a convenient synthesis of chlorinated molecules which are not readily available by other methods.     

Synthesis of 2-(arylthio)benzoates by [3+3] cyclocondensations of 3-arylthio-1-silyloxy-1,3-butadienes with 3-oxo-orthoesters, 1,1,3,3-tetramethoxypropane and 1,1-bis(methylthio)-1-en-3-ones

A variety of 2-arylthio-4-methoxybenzoates are regioselectively prepared by TiCl₄-mediated [3+3] cyclocondensations of 3-arylthio-1-trimethylsilyloxy-1,3-butadienes with 3-oxo-orthoesters. Unsubstituted 2-(arylthio)benzoates were prepared by Me₃SiOTf-catalyzed cyclization of 3-arylthio-1-trimethylsilyloxy-1,3-butadienes with 1,1,3,3-tetramethoxypropane. The TiCl₄-mediated cyclization of 3-arylthio-1-trimethylsilyloxy-1,3-butadienes with 1,1-bis(methylthio)-1-en-3-ones results in regioselective formation of 2-arylthio-6-(methylthio)benzoates.     

Visible Light-Mediated Cyclisation Reaction for the Synthesis of Highly-Substituted Tetrahydroquinolines and Quinolines

Condensation of 2-vinylanilines and conjugated aldehydes followed by an efficient light-mediated cyclisation selectively yields either substituted tetrahydroquinolines with typically high dr, or in the presence of an iridium photocatalyst the synthesis of quinoline derivatives is demonstrated. These atom economical processes require mild conditions, with the substrate scope demonstrating excellent site selectivity and functional group tolerance, including azaarene-bearing substrates. A thorough experimental mechanistic investigation explores multiple pathways and the key role that imine and iminium intermediates play in the absorption of visible light to generate reactive excited states. The synthetic utility of the reactions is demonstrated on gram scale quantities in both batch and flow, alongside further manipulation of the medicinally relevant products.     

One-pot synthesis of aryl fluorides by [3+3] cyclization of 1,3-bis(silyl enol ethers) with 2-fluoro-3-silyloxy-2-en-1-ones

Functionalized aryl fluorides were regioselectively prepared by [3+3] cyclization of 1,3-bis(silyl enol ethers) with 2-fluoro-3-silyloxy-2-en-1-ones.