Direct Synthesis of Vinylene Carbonates from Aromatic Aldehydes**

Abstract

Substituted vinylene carbonates were directly prepared from aromatic aldehydes following a one‐pot Benzoin condensation/transcarbonation sequence under solvent‐free conditions. The combination of a N‐phenyl substituted triazolium salt NHC precursor and 4‐dimethylaminopyridine (DMAP) was found essential to reach high yield and selectivity. The reaction scope was investigated with a range of aromatic aldehydes and the corresponding vinylene carbonates were obtained with 32–86 % isolated yields (14 examples).

An Organocatalytic Route to endo‐Vinylene Carbonates from Carbon Dioxide‐Based exo‐Vinylene Carbonates

“…The ketone‐carbonate species in the work of Duguet's group was shown to be the key intermediate for the preparation of endo ‐VCs [18,19] . At the same time, exo ‐VCs are reported to yield these ketones through the ring‐opening reaction with several nucleophiles [5a,7a] .…”

“…The ketone-carbonate species in the work of Duguet's group was shown to be the key intermediate for the preparation of endo-VCs. [18,19] At the same time, exo-VCs are reported to yield these ketones through the ring-opening reaction with several nucleophiles. [5a,7a] Therefore, our hypothesis was that with a suitable catalytic system based on an alcohol and a base for a reversible ring-opening, exo-VCs could be transferred into the corresponding endo-VCs.…”

“…[18] They also managed to further improve this method using more accessible arylaldehydes as starting materials, which form α-hydroxy ketones insitu. [19] While these benzoin-or acyloin-related transformations exclusively use secondary alcohol precursors for the synthesis of di-substituted endo-VCs, methodologies starting from primary alcohol precursors to synthesize mono-substituted endo-VCs remained undeveloped. We therefore report here an Nheterocyclic base-catalyzed exo-VC to endo-VC isomerization in good to excellent yields with PhOH as co-catalyst, allowing to start from both primary and secondary alcohol precursors.…”

“…Duguet and co‐workers developed a route using diphenyl carbonate (DPC) as carbonyl source and α‐hydroxy ketones to synthesize endo ‐VCs (Scheme 1c) [18] . They also managed to further improve this method using more accessible arylaldehydes as starting materials, which form α‐hydroxy ketones in‐situ [19] . While these benzoin‐ or acyloin‐related transformations exclusively use secondary alcohol precursors for the synthesis of di‐substituted endo ‐VCs, methodologies starting from primary alcohol precursors to synthesize mono‐substituted endo ‐VCs remained undeveloped.…”

Chemical upcycling of poly(bisphenol A carbonate) to vinylene carbonates through organocatalysis

“…34 Recently, our group has demonstrated that diphenyl carbonate (DPC) can be used as a cheap and non-toxic carbonyl source for the preparation of vinylene carbonates from either benzoins/acyloins 35 or directly from aldehydes. 36 Based upon these previous studies, we now report here our results on the preparation of vinylene carbonates using poly(bisphenol A carbonate) as a carbonyl source, thus concomitantly leading to the chemical upcycling of this polymer (Fig. 1).…”