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Polycondensation of Butenediol: Synthesis of Telechelic 2-Butene-1,4-diol Oligomers
Kiesewetter, Matthew K.,Edward, Justin A.,Kim, Hyunuk,Waymouth, Robert M. American Chemical Society 2011 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.133 No.41
<P>The catalytic condensation of <I>cis</I>-2-butene-1,4-diol with CpRu(MQA)(C<SUB>3</SUB>H<SUB>5</SUB>) (Cp = cyclopentadienyl, MQA = 4-methoxyquinoline-2-carboxylate) generates poly(2-butenediol), an unsaturated telechelic polyether diol with molecular weights between 400 and 4600 g/mol. This Ru(IV) allyl catalyst enchains 2-butene-1,4-diol primarily as the linear <I>trans</I>-2-butenyl ether (92%) along with vinyl branches (8%). These telechelic oligomers are useful chain extenders and macromonomers, as demonstrated by their use in the synthesis of poly(lactide)-<I>b</I>-poly(butenediol)-<I>b</I>-poly(lactide) triblock copolymers. Model studies support a proposed mechanism involving the formation of Ru(IV) allyl intermediates from allylic alcohols and chain growth by selective nucleophilic displacement at the terminus of the Ru(IV) allyl to generate <I>trans</I>-2-butenyl ether linkages.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2011/jacsat.2011.133.issue-41/ja207465h/production/images/medium/ja-2011-07465h_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja207465h'>ACS Electronic Supporting Info</A></P>
Organocatalytic Synthesis of Quinine-Functionalized Poly(carbonate)s
Edward, Justin A.,Kiesewetter, Matthew K.,Kim, Hyunuk,Flanagan, James C.A.,Hedrick, James L.,Waymouth, Robert M. American Chemical Society 2012 Biomacromolecules Vol.13 No.8
<P>The ring-opening polymerization of substituted cyclic carbonates with 1-(3,5-bis-trifluoromethyl-phenyl)-3-cyclohexyl-thiourea (TU)/1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) organocatalysts afford highly functionalized oligocarbonates. The fluorescent alkaloid quinine can be readily incorporated into the oligocarbonates either by initiation from quinine or by ring-opening polymerization of a quinine-functionalized cyclic carbonate (MTC-Q). Copolymerization of MTC-Q with a boc-protected guanidinium cyclic carbonate affords, after deprotection, highly water-soluble cationic copolymers functionalized with both quinine and pendant guanidinium groups. When multiple quinine groups are attached to the oligomers, they exhibit minimal fluorescence due to self-quenching. Upon hydrolysis, the fluorescence intensity increases, providing a potential strategy for monitoring the hydrolysis rates in real time.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/bomaf6/2012/bomaf6.2012.13.issue-8/bm300718b/production/images/medium/bm-2012-00718b_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/bm300718b'>ACS Electronic Supporting Info</A></P>