Fig. 3: Mechanistic studies.

a, Interception of a ketene intermediate with diethylamine. b, A reaction using ¹³C-labelled 1a. c, Isolation of a siloxycarbene–palladium 6. ORTEP drawing of 6 with thermal ellipsoids set at the 50% probability level is shown (for details, see Supplementary Fig. 5). THF, tetrahydrofuran.