Ph₂P(O) is a new terminal alkyne protecting group, developed by Orita and Otera et al. This protecting group can be introduced readily to terminal alkynes by CuI catalyzed phosphination using chlorodiphenylphosphine [C0597] and subsequent oxidation with H₂O₂. The high polarity of the phosphoryl group enables easy separation of the desired products from the lower polar hydrocarbon byproducts. The Ph₂P(O)-protected ethynes can be easily deprotected by treatment with t-BuOK.
This product, HC≡C-P(O)Ph₂, is a “ready-to-use” mono-protected acetylene, can be applied to a one-pot synthesis of phenyleneethynylenes used for electronic devices.