Synthesis and polymerisation of α-alkylidene cyclic carbonates from carbon dioxide, epoxides and the primary propargylic alcohol 1,4-butynediol

Abstract

Using the bulk chemical 1,4-butynediol, readily available epoxides and carbon dioxide, a new series of unsubstituted exovinylene carbonates were synthesised.

Liquid‐liquid‐phase Synthesis of exo‐Vinylene Carbonates from Primary Propargylic Alcohols: Catalyst Design and Recycling

“…The competing ring‐opening reactions (Table 2, products B , 4 %) appear to be in part responsible for the decreased selectivity. This fate is supported by two methylene signals in the 1 H NMR at approximately δ H =4.7, which is in line with similar ring‐opened products [5,20] . Furthermore, in the 13 C NMR, signals indicative of the ketone moiety ( δ C =202) and a new carbonate group ( δ C =154) are present.…”

“…Signals in the proton NMR spectrum indicative of ring‐opened products ( B ) at approximately δ H =4.7 suggest that this is the major fate of the remaining converted propargylic alcohol (28–33 %). In contrast, our previously reported catalytic system (DavePhos/AgOAc) affords a 93 % yield of the corresponding bis‐EVC after chromatography [5] …”

“…Two different nucleophilic attacks of the EVC carbonate are possible, due to the presence of a primary alcohol in the starting material and a secondary alcohol in both the substrate and the product. Both intuitively, and also supported by experiment, the primary alcohol is the more likely nucleophile [5] . Quantitative conversions can be achieved by increasing catalyst loading to [Ag]/L=2/2.5 mol% (entry 2), however with increased catalyst loading, the selectivity towards EVC decreases to 72 %, with a concomitant increase in the yield of ring‐opened products (9 %).…”

“…Therefore, in our first attempts to isolate the products from the silver catalyst, following initial phase separation, the polar phase was washed two additional times with the hydrophobic solvent to reduce the silver concentration further to 80 ppm. Despite removing most of the catalyst, concentrating the solution resulted in destruction of the EVC unit, presumably due to the nucleophilic attack of the secondary alcohol and the formation of oligomers [5] . This reaction is suppressed by first treating the acetonitrile phase with methanolic HCl and filtering the solution over Celite.…”

Silver(I) Oxide‐/DBU‐Promoted Synthesis of Dihydrofuran Units through Allenyl Silver Formation

“…Indeed, due to its [Kr] 4d 10 5s 1 configuration, silver possesses as trong alkynophilicity and its ability to p-coordinate to unsaturated systems having low-lying empty orbitals makes it extremely interesting especially in the field of alkyne-based chemistry. [15] In ap reliminary survey,w e chose the combination of Ag 2 O/1,8-diazabicyclo [5.4.0]undec-7ene (DBU) in acetonitrile and 1,3-ketoe ster 1a as the substrate (Scheme 1).…”