“…Thes ubstituents directlyboundtothe alkynefunction(Scheme 2, R 1 ), as well as the substituents directly bound to thec arbonyl function( R 2 ) were varied with thei ntent to probeb oth steric ande lectronic effects on thedynamicexchange.Inthisseries of alkynones,but-3-yn-2-one (X = 1)was arbitrarily selected as thebenchmark to which allother alkynones willbecompared.Alkynones 2, 13-15 were chosent oe valuate the effecto fr eplacing the ketone functionality with an ester,a mide,s ulfonamide, or sulfone, respectively,a st hese area lso common moieties in polymer chemistry.A lkynones 3-9 represent derivatives of 1-phenylprop-2-yn-1-one,w hich allowedt he exploration of theh ypothetical control on thee xchange through introductiono f electronically (de)activating para-substituents.A lkynones 10-12 were chosen to evaluate thee ffect ofs ubstituentsd irectly boundt ot he alkyne function. All alkynonesw ere synthesized according to known literature procedures [37][38][39][40][41][42] (see theSupport-ingI nformation),e xceptf or alkynones 1, 2 and 12,w hich are commerciallyavailable.…”