Table 2. Scope of the Catalytic Synthesis of Cyclopropenium Cations 3^a.

^aPerformed with alkyne 1 (0.26 mmol, 1.3 equiv), hypervalent iodine reagents 2 (0.2 mmol, 1.0 equiv), CH₂Cl₂, −60 °C, 50 min, 1,3,5-trimethoxybenzene (0.8 mmol, 4.0 equiv) was added for the synthesis of 3*.

^bYield of the reaction to give 1.08 g of 3a and 1.10 g of 3ad.

^c1.5 mol % catalyst.

^d2 mol % catalyst.

^eReaction carried out at −63 °C.

^f1.5 equiv of alkyne.

^g2.0 equiv of alkyne.