Fig. 8. (A) Distortion–interaction analysis at the transition state for the reactions of the sulfonium ylide 7 with 2a, 5a and 5b at the SMD(DMSO)/M06-2X/6-31+G(d,p) level of theory. (B) Illustration of the pyramidalization Δ. (C) SAPT analysis for the reaction of 7 with 5a and 5b, respectively, at the sSAPT0/jun-cc-pVDZ level of theory in gas-phase.