A mild, general, and functional group tolerant intramolecular hydroalkoxylation and hydroacyloxylation of unactivated olefins using a Co(salen) complex, an N-fluoropyridinium salt, and a disiloxane reagent is described. This reaction was carried out at room temperature and afforded five- and six-membered oxygen heterocyclic compounds, such as cyclic ethers and lactones. The Co complex was optimized for previously rare medium ring formation by hydrofunctionalization of unactivated olefins. The powerful Co catalyst system also enables the deprotective hydroalkoxylation of O-protected alkenyl alcohol and hydroacyloxylation of alkenyl ester to afford cyclic ethers and lactones directly. The substrate scope and mechanistic proof of deprotection were investigated. The experimental evidence supports the concerted transition state of the bond-forming step involving a cationic Co complex.

We developed an addition reaction of fluorous solvents to olefins using salen-cobalt (Co) complex, N-fluoro-2,4,6-trimethylpyridinium tetrafluoroborate, and 1,1,3,3-tetramethyldisiloxane. This reaction condition was found to activate olefins, which enabled them to be attacked by 2,2,2-trifluoroethanol (TFE) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), both of which are electronically weak nucleophiles.

A revised structure for trichodermatide A, which is a C10 epimer of the originally reported structure, is proposed. The revision is supported by the X‐ray structure of a synthetic intermediate synthesized according to our previous route for trichodermatide A. The revised stereochemistry was also supported by NOESY experiment. Finally, we synthesized Trauner's compound corresponding to the originally reported structure from our synthetic intermediate of trichodermatide A through a Mitsunobu reaction at C10.

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