Benzocyclobutenecarboxylic acid

The Kametani group has made considerable use of the intramolecular trapping of benzynes by pendant carbanion centers. The nitrile (133) is a key and versatile intermediate in many of the K etani studies, including the preparation of optically pure estradiol. The ester of the benzocyclobutenecarboxylic acid (134) was prepared by a similar benzyne cyclization. The acid (134) was converted via oxidative decarboxylation and HCl hydrolysis to the very labile tra/t5-2-arylbenzocyclobutenol (135), which was used in the preparation of p ophyllotoxin. ... 

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