Density functional theory investigation of the reaction of isodiiodomethane with acetylene: potential utility of isodiiodomethane for cyclopropenation reactions

We present density functional theory calculations for the reactions of CH2I-I and CH2I with acetylene (HC triple bond CH) to form a cyclopropene product. CH2I-I readily reacts with HC triple bond CH to form a cyclopropene product and an I2 leaving group via a rate-determining step barrier of approximately 3.9 kcal/mol (B3LYP/Sadlej-pVTZ). Calculations indicated that the CH2I radical reacts to form an iodopropenyl radical, which can close to a cyclopropene only with difficulty. Our results indicate that CH2I-I may act as an effective carbenoid to produce cyclopropenated products from alkynes.