Microwave irradiation, aryl alcohols

BKC115>. Amides derived from aromatic carboxylic acids and benzotriazole were reported to form 2-aryl-5,6-dihydro-4//-l,3-oxazines with 3-aminopropanol in excellent yields when subjected to microwave irradiation in the presence of SOCI2 <2004JOC811 >. Imidates have often been applied to cyclize 1,3-amino alcohols directly to 5,6-dihydro-l,3-oxazine derivatives <1996ACS922, 2004JHC69, 2004JHC367>. 

Trabanco and coworkers developed an operationally simple method for the a-allylation of aryl alkanones with ally] alcohol under microwave irradiation conditions (Scheme 10.35) [77]. The corresponding a-allyl ketones were obtained in moderate to good yields with minor quantities of diallylation by-products. 

Regenerable, ion-supported (diacetoxyiodo)benzenes promoted the formation of 5-aryl-2-methyl oxazoles from acetophenones and acetonitrile in the presence of CF3SO3H with excellent yields and purity (13T2961). A procedure for the synthesis of oxa(thia)zol-3-yl methyl alcohols 135 started from 3-oxetanone 133 and (thio)amides 134.The reaction proceeds under microwave irradiation and acid catalysis (13CEJ9655). 

A combination of palladium acetate and tricyclohexylphosphine is an effective catalyst. The allyl transfer reactions proceed in the presence of the catalyst and cesium carbonate in refluxing toluene. Homoallylic alcohol 1 transfers the methallyl group to a variety of aryl halides (Scheme 5.9) [12b]. The reactions under microwave irradiation at 250 "C go to completion in 15 min [12c]. The catalyst loading can be reduced to 0.05 mol% in the reaction of ethyl chlorobenzoate under microwave heating. 

Okuma et al. (2013) described a simple, rapid and efficient green synthesis of aryl methoxylated benzamides and 2-oxazolines from renewable Eucalyptus biomass-tar derivatives. One pot synthesis was realized using microwave irradiation as an alternative energy source, through a direct condensation reaction of amino alcohol with carboxylic acids as starting materials. 

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