The Hydroboration of 3-Chloro-1-iodo-1-propyne with Dialkylboranes, and its Application to the Syntheses of Some Geminally Dialkylated Propene Derivatives

Article abstract of DOI:10.1246/bcsj.65.3294

3-Chloro-1-iodo-1-propyne is smoothly hydroborated with dialkylboranes, giving (Z)-(3-chloro-1-iodo-1-propenyl)dialkylboranes exclusively.Subsequent treatment of the hydroboration mixture with sodium methoxide or aqueous sodium hydroxide results in migration of two alkyl groups from the boron atom to the α-alkenyl carbon atom to provide dialkylated allylboranes, which are protonolyzed with methanol or water to produce 1,1-dialkyl-1-propenes.Oxidation of the allylboranes with alkaline hydrogen peroxide prior to protonolysis gives 1,1-dialkyl-2-propen-1-ols.Treatmentof (Z)-(3-chloro-1-iodo-1-propenyl)dicyclohexylborane with Grignard reagents, followed by protonolysis with acetic acid, provides 3-alkyl-3-cyclohexyl-1-propenes in which the alkyl group is derived from Grignard reagent.