Phenol ring acetylene derivs

Phenol ring. 5-(2-Methyl- Acetylene derivs. 5-(4-Methoxy-... 

Phenols can be formed also in rearrangements of small carbocyclic rings, starting from cyclopropane derivatives. For instance, the reaction of benzoylcyclopropene 345 with acetylenes 346 in the presence of 10 mol% of [ClRh(CO)2]2 results in the oxepines 347 and phenols 348. 

As shown in Scheme 1.46, a simple synthesis of complex fused 1,4-benzoxaz-epin-2-one derivatives 86 and 87 was aehieved via a three-component leaction of quinoline or isoquinoline, acetylene dicaiboxylic esters and l-(6-hydioxy-2-isopio-penyl-l-benzofman-yl)-l-ethanone in water, in the absence of aiy catalyst [68]. Presumably, this transformation proceeds via the initial formation of a 1 1 zwitter-ionic intermediate 88 from the Michael addition of isoquinohne (or quinolone) to the activated ester. A proton transfer reaction takes then place in which this species is protonatedby the phenol group in the l-(6-hydroxy-2-isopropenyl-l-benzofuran-yl)-l-ethanone substrate, and this is followed by a second Michael addition of the resulting phenoxide anion to the isoquinohnium ion to afford intermediate 88, containing benzofuryl and isoquinoline ring systems. This intermediate then undergoes... 

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