A fast double-stage convergent synthesis of dendritc polyethers

Abstract

200F, 3001 Leuven (Heverlee), Belgium Two tert-butyldiphenylsilyl-protected synthons 7 and 9 are prepared in excellent yields and used in a one-pot synthesis of higher generation polyether dendrons.

Dendritic Oligoethers

“…An accelerated convergent synthesis of the Fréchet's dendrons was recently developed by L'abbé and coworkers using hyperbranched AB 4 25 or AB 8 26 as the monomer units [12]. Thus, treatment of benzyl alcohol 27, prepared from methyl 3,5-dihydrobenzoate via sequential silylation and reduction, with methyl 3,5-dihydroxybenzoate under Mitsunobu conditions afforded ester 28 (Scheme 8).…”

Functionalizing the interior of dendrimers: Synthetic challenges and applications

“…72 Monomer 22 was readily available because methyl gallate could be selectively deprotonated and, therefore, allylated on account of the higher acidity of the 4-hydroxy group. All eight different combinations of inner dendrons 24-27 and outer dendrons 28-31 were prepared and then combined with a double-stage convergent growth approach [73][74][75] to afford a total of 16 fourthgeneration dendron structures (32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47). Methyl benzoates, rather than benzylic alcohols, were used for growth because alkylations proceed with higher degrees of regioselectivity, i.e., no O-alkylation is observed, and the additional reduction step is facilitated by workup with Baeckström's reagent.…”

Dendrimers with Thermally Labile End Groups: An Alternative Approach to Chemically Amplified Resist Materials Designed for Sub-100 nm Lithography

“…Unfortunately, the t-BOC series of dendrimers could not be synthesized using the standard Williamson ether coupling conditions [21] due to the lack of stability of the t-BOC protected phenols towards such basic conditions. Hence, we adopted a strategy from L'AbbØ, et al [24] , which was used for the synthesis of silyl ether terminated dendrons. This approach utilized a Mitsunobu [25] etherification for the coupling step combined with a reductive activation step.…”