Synthesis of diaryl ethers based on one-pot [3+3] cyclizations of 1,3-bis(silyl enol ethers)

Functionalized and sterically encumbered diaryl ethers were prepared by [3+3] cyclization of 1,3-bis(silyl enol ethers) with 2-aryloxy-3-(silyloxy)alk-2-en-1-ones.     

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.     

Synthesis of phthalates and isophthalates by [3+3] cyclizations of 1,3-bis(silyl enol ethers) with 3-(silyloxy)alk-2-en-1-ones

3-Hydroxyphthalates and 4-hydroxyisophthalates were prepared by sequential [3+3] cyclization reactions of 1,3-bis(silyl enol ethers) with 2- and 3-alkoxycarbonyl-3-(silyloxy)alk-2-en-1-ones.     

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 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.     

Efficient synthesis of salicylates by catalytic [3 + 3] cyclizations of 1,3-bis(silyl enol ethers) with 1,1,3,3-tetramethoxypropane

Salicylic acid derivatives were prepared by Me3SiOTf-catalyzed [3 + 3] cyclization of 1,3-bis(silyl enol ethers) with 1,1,3,3-tetramethoxypropane.     

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 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 functionalized acetophenones by [3 + 3] cyclizations of 1,3-bis-silyl enol ethers with 2-acetyl-3-silyloxyalk-2-en-1-ones

The TiCl₄ mediated cyclization of 1,3-bis-silyl enol ethers with 2-acetyl-1-silyloxybut-1-en-3-one and 3-acetyl-4-silyloxypent-3-en-2-one, readily prepared from 3-formyl(acetylacetone) and triacetylmethane, afforded a variety of functionalized acetophenones.     

Regioselective synthesis of 4-chlorophenols, 10-chloro-7-hydroxy-6H-benzo[c]chromen-6-ones, and 4-chloro-1-hydroxy-9H-fluoren-9-ones based on [3+3] cyclizations of 1,3-bis(silyloxy)-1,3-dienes with 2-chloro-3-silyloxy-2-en-1-ones

A variety of 4-chlorophenols, 10-chloro-7-hydroxy-6H-benzo[c]chromen-6-ones, and 4-chloro-1-hydroxy-9H-fluoren-9-ones were prepared by formal [3+3] cyclizations of 1,3-bis(silyloxy)-1,3-dienes with 2-chloro-3-(silyloxy)alk-2-en-1-ones.     

Synthesis of functionalized 2-alkoxybenzoates, 2-aryloxybenzoates and xanthones based on formal [3+3] cyclocondensations of 3-alkoxy- and 3-aryloxy-1-silyloxy-1,3-butadienes with 3-silyloxy-2-en-1-ones

Functionalized 2-alkoxy- and 2-aryloxybenzoates were prepared by formal [3+3] cyclocondensations of 3-alkoxy- and 3-aryloxy-1-silyloxy-1,3-butadienes with 3-silyloxy-2-en-1-ones. The reaction of 2-aryloxybenzoates with concentrated sulfuric acid resulted in the formation of xanthones.     

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.     

Regioselective synthesis of 2-acetyl- and 2-alkoxycarbonyl-3-(trifluoromethyl)phenols by [3+3] cyclization of 1,3-bis-silyl enol ethers with 4-ethoxy- and 4-silyloxy-1,1,1-trifluoroalk-3-en-2-ones

2-Acetyl- and 2-alkoxycarbonyl-3-(trifluoromethyl)phenols were prepared by [3+3] cyclization of 1,3-bis-silyl enol ethers with 4-ethoxy- and 4-silyloxy-1,1,1-trifluoroalk-3-en-2-ones.     

First synthesis of functionalized 5-aryl-3-(trifluoromethyl)phenols by regioselective [3+3] cyclocondensations of 1,3-bis(silyloxy)-1,3-butadienes with 3-aryl-3-silyloxy-1-trifluoromethyl-2-en-1-ones

A variety of functionalized 5-aryl-3-(trifluoromethyl)phenols were prepared by the first TiCl₄-mediated [3+3] cyclocondensation of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with 3-aryl-3-trimethylsilyloxy-1-trifluoromethyl-2-en-1-ones.     

Synthesis of 7-hydroxy-2-(2-hydroxybenzoyl)benzo[c]chromen-6-ones by sequential application of domino reactions of 1,3-bis(silyl enol ethers) with benzopyrylium triflates

The domino, Michael-retro-Michael-aldol, reaction of 2,4-bis(trimethylsilyloxy)penta-1,3-diene with 3-formylchromones afforded 4-(2-hydroxybenzoyl)-2-acetylphenols, which were transformed into 6-(2-hydroxybenzoyl)chromones. The Me₃SiOTf-mediated condensation of the latter with 1,3-bis(silyl enol ethers) and subsequent domino ‘retro-Michael-aldol-lactonization’ reaction afforded 7-hydroxy-2-(2-hydroxybenzoyl)benzo[c]chromen-6-ones.     

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.     

Synthesis of functionalized 4-chlorophenols and 1,4-dihydroquinones by [3+3] cyclization of 1,3-bis-silyl enol ethers with 2-chloro- and 2-acyloxy-3-(silyloxy)alk-2-en-1-ones

Functionalized 4-chlorophenols and 1,4-dihydroquinones were prepared by [3+3] cyclization of 1,3-bis-silyl enol ethers with 2-chloro- and 2-acyloxy-3-(silyloxy)alk-2-en-1-ones.     

Synthesis of functionalized p-dihydrobenzoquinones and p-benzoquinones based on [3+3] cyclizations of 1,3-bis-silyl enol ethers

Functionalized mono-protected p-dihydrobenzoquinones were prepared by [3+3] cyclization of 1,3-bis-silyl enol ethers with 2-acyloxy-3-(silyloxy)alk-2-en-1-ones. Deprotection and oxidation of the products afforded the corresponding p-benzoquinones.     

Formal [4+2] cycloaddition between 3-ethoxycyclobutanones and silyl enol ethers

3-Ethoxycyclobutanones reacted with silyl enol ethers to give formal [4+2] cycloadducts, 3-ethoxy-5-trimethylsiloxycyclohexanone derivatives, by using ethylaluminum dichloride as a Lewis acid. Highly oxygenated cyclohexanone derivatives were stereoselectively prepared by this method.