NOVEL METHODS FOR INTRODUCING A TWO-CARBON UNIT AT EITHER THE 3- OR 4-POSITION OF THE ISOQUINOLONE RING BY MEANS OF PHOTO[2+2]CYCLOADDITION REACTION

A novel method is described for introducing a two-carbon unit at either the 3- or 4-position of the 1-isoquinolone ring. The method for the synthesis of the 4-vinyl or 4-ethynyl derivative of isoquinolone consists of 1) photo-addition of the isoquinolone to chloroethylenes and 2) base treatment of the major (head-to-tail) adduct giving the 4-substituted isoquinolones. Similarly, by using 3-methoxyisoquinolone and vinyl acetate in step 1) and an acidic condition in step 2), a formylmethyl group is introduced into the 3-position of the isoquinolone ring.