Synthesis of Polyglycerol, Porphyrin-Cored Dendrimers Using Click Chemistry.

Polyglycerol, porphyrin-cored dendrimers were synthesized by the click reaction of azide-cored polyglycerol dendrons and octaazidoporphyrin . The dendrons were synthesized divergently starting with TBDPS protected allyl alcohol . Two, three and four cycles of dihydroxylation-allyl etherification gave dendrons [G-2.5] , [G-3.5] , [G-4.5] , with four, eight, and sixteen alkene groups, respectively. Dendron was readily prepared on large scale with an overall yield of 45%. Dendron was deprotected and converted to the corresponding alkyne - and azide-cored dendron and in 89% and 75% yield, respectively. Dendron was deprotected and converted to the corresponding alkyne - and azide-cored dendron and in 68% and 24% yield, respectively. Both the [G-3.5]-azide and [G-4.5]-azide were separately "clicked" to polyalkyne core via the Huisgen 1,3-dipolar cycloaddition to afford and in 65% and 66% yield, respectively. Dendrimer has a MW ~ 16,000 and 128 peripheral alkene groups.