| Abstract
| - The reactions of 3-butyn-2-one (1), 3-hexyn-2-one (2), and 4-phenyl-3-butyn-2-one (3) with brominechloride (BrCl) and iodine monochloride (ICl) in CH2Cl2, CH2Cl2/pyridine, and MeOH are described.The data show that the major products in CH2Cl2 are (Z)-AM (anti-Markovnikov) regioisomers.With the exception of 3 and ICl, the (E)-AM regioisomers predominate when pyridine was addedas an acid scavenger. Minor amounts of the M regioisomers were formed with 1 and 2 and BrCl.The percentage of M regioisomer increased significantly with 1 and BrCl in MeOH, but MeOH hadlittle affect on the other reactions. Isolation and stability of the products are discussed. Detailedevidence for the structures of the products, involving a combination of MS, 1H and 13C NMR, andIR, is presented; HRMS analyses are provided as proofs for all of the products. The acid-catalyzedmechanism and the halonium ion mechanism are considered as possible pathways in the formationof the products.
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