Theoretical Investigation on Mechanism of the PPh₃-Catalyzed Isomerization of Allenic Sulfones to 2-Arylsulfonyl 1,3-Dienes: Effects of Additive as the Proton-Shuttle

Abstract

The PPh3‐catalyzed isomerization of allenic sulfones to form 2‐arylsulfonyl 1,3‐dienes is used to explore the effects of additive as the proton‐shuttle using the DFT method. The calculated results show that the additive as a proton‐shuttle agent can greatly reduce the energy barrier of proton‐transfer process. More importantly, our calculations reveal that the difference of proton‐shuttle agents in the catalytic captivity is primarily attributed to their acidity (AcOH > PhOH > EtOH ≈ H2O). The catalytic activity order of proton‐shuttle agents is AcOH < PhOH < EtOH ≈ H2O for the proton‐transfer process. Our present calculations not only explain the experimental phenomena well, but also put forward some guidance and advice for the selection of proton‐shuttle agent in the organic catalytic reactions containing the proton‐transfer process.

Rational selection of co-catalysts for the deaminative hydrogenation of amides

“…formanilide and acetamide), 5 when they are used in catalytic concentrations their consumption is slower than that of the reactants, enabling their cocatalytic effect. 13 The ability of each potential co-catalyst to assist with the hemiaminal proton transfer 5,18,19 involved in the C-N bond cleavage (step 2 in Scheme 1) was quantied by computing the transition state(s) associated with this process (DG ‡ HT ; Scheme 2 and Fig. 1), which can be either concerted (with TBD, methanol and morpholine) or step-wise (all other cocatalysts).…”