@Vy_Dong_Group There’s a nice recent @VarinderAggar11 group publication displaying this type of photocatalytic radical polar crossover reactivity for acyl iminium ion generation in the context of alpha amino phosphonate synthesis: https://t.co/fLw23Dsn9P
I'm excited to be taking part in this year's #RSCPoster conference! From our recent work, we introduce a new photochemical method to prepare a wide variety of saturated heterocycles from bifunctional redox active ester reagents and alkenes.
Paper: https://t.co/gbZ71Bs8pw
#RSCOrg
@Vy_Dong_Group However, these were unsuccessful, we reason that the alpha amino radical that’s generated on decarboxylation is too facile to oxidise to the acyl iminium ion by Ir(IV) prior to the radical engaging with the alkene partner. Unfortunate but glad we tried!
@sudhir859 I think unfortunately not I'm afraid. We observed carbocation hydration products in the presence of exogenous water. However, trifluoroacetic acid also works as the Brönsted acid additive in most examples, though not quite as well as diphenylphosphate.
@Rhit26215244 Ah I see, I might have misunderstood which example. In this case, the mass balance is remaining starting material for the febuxostat alkene, and protodecarboxylation product (decarboxylation then HAT termination) of the celecoxib NHPI ester (essentially the N-ethyl sulfonamide).
@g_laudadio We didn't look hard at speciation in this work beyond this timecourse study, but that's our hypothesis for phosphate O-trapping. We didn't observe any radical phosphorylation (at P), and didn't look beyond Brönsted acid additives. TFA also works but phosphate was most general.
@g_laudadio In the six membered ring examples in particular, we think that phosphate may be trapping the carbocation prior to later SN1 or SN2 type cyclisation. In these, we see a lag between NHPI consumption and product formation, looking there's an intermediate prior to ring closure.
@Rhit26215244 Thank you! This febuxostat example was well behaved and we saw only this annulation product. In some other substrates, we would occasionally see linear termination (HAT outcompetes RPC) or desaturation (E1 type) products. We detail poorly performing examples in the Supp Info.
@meher_rajpoot For some related, net-oxidative radical polar crossover catalysis, see these awesome papers from @uwyoongroup:
https://t.co/8spbsGdPwn
https://t.co/xzRcLoFiRH
@meher_rajpoot Thank you for your feedback and question! We could potentially use carboxylic acids directly in the presence of an oxidant, but in the context of this transformation, we haven't actively explored.
I'm grateful for the opportunity to have carried out this project in a collaboration between the Knowles research group @PrincetonChem, and the Doyle research group @uclachem. We kindly acknowledge financial support from @MSCActions.
Excited to share my first first author paper, out now in #orglett. If you’re interested in asymmetric radical chemistry, amine synthesis or CATs please check it out. Thanks to Aaron (@TrowbridgeGroup) and @MatthewGaunt8 👩🏻🔬📄https://t.co/lXqqGstpga @JOC_OL
#ICIQJobs
2️⃣ positions to discover and develop new chemical reactions based on equivalents of carbyne species
▶️ https://t.co/3C6UOJHVAr
⏩ https://t.co/JYto4RQsbp
1️⃣ position to exploit and develop a proprietary technology
🔎 https://t.co/7nrW1bSYFw
⏳ Apply before Jan, 15