Enolesters as chain end‐functionalizing agents for the living ring opening metathesis polymerization

Abstract

Functional enolethers have previously been used to introduce functional end groups at the chain end of ruthenium carbene complex initiated living ring opening metathesis polymers. Here, we investigated whether the weaker p-donating enolesters could equally be used in regio selective reactions with ruthenium carbene complexes and thus as polymer endfunctionalization reagents. Enolesters such as vinyl acetate, butenyl acetate, 3-(4-(tert-butoxy)phenyl)propenyl acetate and 6-(((benzyloxy)carbonyl)amino)hex-1-en-1-yl acetate were used as living ROMP terminating agents. All gave the expected end groups proving that enolesters are synthetically easily accessible targets for living ROMP end-functionalization.

Heterotelechelic Polymers by Ring‐Opening Metathesis and Regioselective Chain Transfer

“…Two mass distributions, one with an alcohol and another with a phenyl end‐group, could be distinguished in the MALDI ToF mass spectrum (Supporting Information). A similar difference in selectivity was recently observed for the reaction of G1 and G3 with vinyl acetates . Furthermore, neither cinnamic aldehyde nor cinnamic acid showed any regioselectivity in the reaction with G1‐initiated poly(MNI).…”

Functional Metathesis Catalyst Through Ring Closing Enyne Metathesis: One Pot Protocol for Living Heterotelechelic Polymers

“…Many methods have been described to prepare polymers with alcohol, thiol, carboxylic acid, aldehyde or amine end groups in addition to the introduction of entire groups and moieties. [12], [13], [14], [15], [16], [17], [18], [19], [20] Sacrificing the living character of the polymerization allows the synthesis of homo-telechelic polymers (Figure 1), typically from monomers such as cyclooctene or cyclooctadiene. [21], [22], [23], [24] Exploiting the propagation and cross-metathesis kinetics of the Grubbs' 3 rd generation complex, homo-telechelics can also be prepared in a living manner.…”

“…Mono end-functional polymers can be made by functionally terminating living ring opening metathesis polymerizations. Many methods have been described to prepare polymers with alcohol, thiol, carboxylic acid, aldehyde or amine end groups in addition to the introduction of entire groups and moieties. − …”

Functional End Groups in Living Ring-Opening Metathesis Polymerization

“…In analogy to the cyclic enol esters described above, we also prepared acyclic enol ester derivatives for polymer end-functionalization (Scheme 4C). 22 Such compounds can be readily prepared from a large range of commercially available functional aldehydes or alcohols and introduce the desired functionality to the monotelechelic polymer chain end similar to the enol ether derivatives mentioned above (Scheme 2).…”