That is possible, but you will have to find out for yourself what those reaction conditions are. One suggestion is to use Diiodomethane (CH2I2 , very reactive) to form the methylenedioxy bridge, and to only use a weak base (like aqueous carbonate) to deprotonate the catechol, and react it all at relatively low temperature. That would favor the MD bridge formation over dimerization. I don't know exactly how selective this would be though.