Heck-type reactions of allylic alcohols : Part IV: (2-Substituted)-1-indanones via 5-endo-trig cyclizations

Various conditions have been tested to obtain efficiently 2-methyl-1-indanone via the Pd-catalyzed 5-endo-trig cyclization of 1-(o-bromophenyl)-2-methylprop-2-en-1-ol. High yield (97%) was obtained at 120 °C in DMF with Pd(OAc)2/cinchonine as the catalytic system and NaHCO3 as the base. Use of this procedure for the synthesis of other substituted indanones led to lower yields but replacing thermal heating by microwave heating improved greatly the results.

Under microwave irradiation, the Pd-catalyzed 5-endo-trig cyclizations depicted on the scheme proceed not only more quickly than under thermal heating, but also with higher yields.Figure optionsDownload as PowerPoint slide