(xylyl-phanephos)Pt2+ in combination with XeF2 mediates the consecutive diastereoselective cation-olefin cyclization/fluorination of polyene substrates. Isolated yields were typically in the 60s while enantioselectivies reached as high as 87%. The data are consistent with a stereoretentive fluorination of a P2Pt-alkyl cation intermediate.

Intramolecular addition of O−H and N−H bonds across carbon− carbon triple bonds to form 5-or 6-membered rings with exocyclic methylene groups for ether products and exocyclic methyl groups for imine products is catalyzed by (IPr)Cu(Me) (IPr = 1,3-bis(2,6-diisopropylphenyl)-imidazol-2-ylidene). In a competition study, the cyclization of primary amines was found to be faster than that of alcohols. Kinetic studies for the conversion of 4-pentyn-1-ol reveal that the catalytic reaction is first-order in copper catalyst and zero-order in alkynyl alcohol, and an Eyring analysis yields ΔH ‡ = 18.7(4) kcal/ mol and ΔS ‡ = −26(1) eu. The reaction of 5-phenyl-4-pentyn-1-ol provides (Z)-2-benzylidene-tetrahydrofuran in high yield and with quantitative stereoselectivity. Results from combined experimental and DFT studies are consistent with a mechanism that involves alkyne insertion into a Cu−O alkoxide bond followed by protonolysis upon reaction with free alkynyl alcohol.

Summary In traditional Wacker processes, Pd(II) becomes reduced to Pd(0) after C-O bond formation and β-H elimination and must be reoxidized to the electrophilic Pd(II) state via a stoichiometric oxidant like benzoquinone, CuCl2, or O2. We report herein a Pt-catalyzed Wacker-type process that regenerates the electrophilic Pt2+ state by H− abstraction from a [Pt]-H using an oxocarbenium ion generated from an acetal or ketal under acidic conditions.

A series of phosphine–Pt2+-catalysts is reported, which enable the oxidative cascade cyclization of poly-alkene substrates. When the terminus is appropriately arranged and a catalyst reoxidation mediator is included, several polycyclic all carbon skeletons can be obtained. In one example, a chiral P2Pt+2 catalyst provides up to 79% ee.

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