Repetitive strategy for exponential growth of hydroxy-functionalized dendrons

The synthesis of dendrons with orthogonally protected functional groups, which allows the construction of dendrons in an exponential fashion, is described. The sequence has been carried out on a gram scale for the first, second, and fourth generation. The dendrons have a relatively loose and flexible structure, which should make further growth feasible. Owing to the dendrons' adjustable and broadly applicable substitution pattern, they are the first representatives of a future construction kit for the systematic synthesis of layered dendrimers. The coupling step involves urethane formation.