3-Ethynyl phenol

A reaction flask was charged with 3-ethynyl phenol (0.017 mol), 5 ml of pyridine, and 20 ml of CH2CI2 and treated with the dropwise addition of 1,3,5-benzenetricarboxylic acid chloride (0.0055 mol) dissolved in 10 ml of CH2CI2 and refluxed for 6 hours at 45°C. The resulting yellow solution was washed 3 times apiece with 20 ml of 1M HCl, IMNaOH, and water. The mixture was then dried withNa2S04, filtered, concentrated, and the product was isolated as a yellow powder in 58% yield. 

Obtained by treatment of p-benzoyl-o-[(trimethylsilyl)-ethynyl]phenol in methanol in the presence of potassium fluoride at 25° for 1 h (75%) [533]. 

Preparation from p-acetyl-o-[(trimethylsilyl)-ethynyl] phenol (m.p. 127-129°) via a Sonogashira coupling followed by desilylation [3920], m.p. 100-102° [3920] ... 

PEPE phenyl ethynyl phenol-formaldehyde resin... 

A divergent behavior has been shown by o-arylethynyl-phenols [109] and o-ethynyl-phenols [110] under their Pd-catalyzed carbonylative reactions with vinyl triflates. For example, treatment of o-(phenylethynyl)phenol 64 and 3,3,5,5-cyclohex-l-en-l-yl triflate 65 under usual carbonylative conditions (Scheme 9.31) gives the 3-acylbenzo[h]furan 66 along with the ester 67. 

In contrast, o-ethynyl-phenols 68 undergo a palladium-catalyzed cyclocarbonylation to afford 3-alkylidene-2-coumaranone 69 (Scheme 9.32). The reaction is envisioned to involve the key intermediate 70. The carbonylpaHadium fragment of 70 adds intra-molecularly to the triple bond. The addition proceeds with syn stereochemistry. The resulting a-vinylpalladium intermediate 71 underlies the reductive elimination of Pd (0) to give the 2-coumaranone derivative and the active catalyst Thermal isomerization of the 7. isomer can occur to some extent under the reaction conditions. 

Gallium phenoxide generated from GaCl3 and butyllithium reacted with sily-lacetylene to give o-(P-silylethenyl) phenols [86]. The carbometalation reaction of phenols with chloroacetylene gave o-ethynylated phenols in the presence of a catalytic amount of GaC (Scheme 7.54) [87]. 

An application of copper-catalyzed propargylic etherification has been reported in the synthesis of ustiloxin D (Equation (63)).248 Here, a quaternary center was generated from the unprecedented reaction of a phenol with an ethynyl aziridine. 

Ohe, Uemura et al. further developed this electrocyclization into the [3,3]-sigmatropy of a cyclopropane system substituted with ethynyl and an acyl or an alkenyl group [33]. Thus, treatment of cis-l-acyl-2-ethynylcyclopropanes 125 with 5 mol% Cr CO)5(thf) in the presence of EtgN at rt induced isomerization to phenol derivatives through the [3,3]-sigmatropy of the vinylidene intermediate 126 to give... 

Catalytic cycloisomerization of cis-l-ethynyl-2-vinyloxiranes vas implemented by [Ru(Tp)(PPh3)(CH3CN)2]PF6, which afforded substituted phenols, as shown in... 

Scheme 6.20. This ruthenium catalyst (10 mol%) was active for the cydization of ds-1 -ethynyl-2-vinyloxiranes to afford various 2,6-disubstituted phenols in reasonable yields. Under similar conditions, 1,1,2,2,-tetrasubstituted oxiranes gave the 2,3,6-trisubstituted phenols with a skeleton reorganization [22]. The 1,2-deuterium shift of the alkynyl deuterium of d-Sle was indicative of mthenium vinylidene intermediates (Scheme 6.20).

In the presence of base, alcohols and phenols add l,5-diphenylpenta-l,4-diyn-3-one (72JOU1398). At 40 °C addition occurs at both triple bonds to give a mixture of the 1,5-dialkoxy compound (411), the triketone and the pyran-4-one. On treatment with acid the former compounds are converted into the pyranone. However, at 15 °C only one triple bond is attacked giving the alkoxyvinyl ethynyl ketone (412), but this also forms the pyranone with acid (Scheme 136). 

Activated phenols react readily with aryl ethynyl ketones in the presence of HIT), to give flavylium salts, 3-deoxyanthocyanidins. The method has been extended to aryl di(ynones) to produce dicationic 2,2 -(phenylene)bis(benzopyrylium) salts (Scheme 21) <07EJO2438, 07SL1067>. 

Alkynyl complexes. These complexes, which are readily available by reaction of an alkynyllithium with chromium carbonyl followed by methylation with CH3OSO2F, undergo facile Diels-Alder reactions with dienes to provide a general route to ,p-un-saturated chromium carbene complexes. The latter undergo benzannelation or cyclo-hexadienone annelation on reaction with an alkyne. A (trimethylsilyl)ethynyl complex is useful because benzannelation results in migration of silicon from carbon to oxygen to provide a protected phenol. 

Pyrylinm salts from ethynyl ketones and phenols... 

The aziridine ring opening reaction with phenol derivatives using copper(l) acetate (CuOAc)-DBU was reported by Li et al. [51]. Reaction of ethynyl nosyl-aziridine 170 and p-hydroxytyrosine derivative 169 in the presence of DBU (2 equiv.) and a catalytic amount... 

Li, R, Evans, C.D. and Joullie, M.M. (2005) A convergent total synthesis of ustiloxin D via an unprecedented copper-catalysed ethynyl aziridine ring-opening by phenol derivatives. Organic Letters, 7, 5325-5327. 

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