The synthesis of a second-generation cobalt catalyst for the formation of trans-THF products via the Mukaiyama aerobic oxidative cyclization is reported. Two procedures have been developed with the new water-soluble catalyst that give superior yields and greatly simplify purification compared to the previous catalysts.

The formal [4+3] cycloaddition of 2-alkoxy-1,1-dicarboxylate activated donor-acceptor cyclobutanes with nitrones is disclosed. The reaction forms structurally unique oxazepines in moderate to high yield with a wide scope of nitrones. In most cases either a diastereomeric mixture or a single diastereomer may be formed, depending on the reaction conditions.

Piotrowski, Mattew L.; Dekruyf, Daryyl SR; and Pagenkopf, Brian, "Oxidative cyclization of tertiary pentenol derivatives forming 2,5,5-trisubstituted THF rings and the total synthesis of cyclocapitelline" (2015). Chemistry Publications. 34.

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The Formal [4 + 3] Cycloaddition Between Donor-Acceptor Cyclobutanes and Nitrones. -The reaction leads to structurally unique oxazepines. Depending on the cyclobutane and the conditions used, a diastereomeric mixture or a single diastereomer is isolated. -(STEVENS, A. C.; PALMER, C.; PAGENKOPF*, B. L.; Org. Lett. 13 (2011) 6, 1528-1531, http://dx.doi.org/10.1021/ol200220d ; Dep. Chem., Univ. West. Ont., London, Ont. N6A 5B7, Can.; Eng.) -Jannicke