At the core of many of these projects are the 2-methyleneoxetanes 2 for which we have reported the first and, so far, only general synthesis. The utility and reactivity of 2 is derived from the strained nature of the oxetane ring and the exocyclic enol ether. For example, treatment of 2 with a strong base provides homopropargylic alcohols 3. On the other hand, reaction with a nucleophile, affords ß-substituted ketones 4. An alternative route to functionalized ketones is via arene-catalyzed, reductive ring opening of 2-methyleneoxetanes, providing 5. We also have reported the first synthesis of [2.2.0] fused ketals 6, and the first general syntheses of 1,5-dioxaspiro[3.2]hexanes 7 and 4-oxaspiro[2.3]hexanes 8.
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(2) Dollinger, L. M.; Howell. A. R. J. Org. Chem. 1998, 63, 6782-6783.
(3) Bekolo, H.; Wang, Y.; Howell, A. R. Tetrahedron 2002, 58, 7101-7107.
(4) Hashemzadeh, M.; Howell, A .R. Tetrahedron Lett. 2000, 41, 1855-1858.
(5) Wang, G.; Wang, Y.; Arcari, J. T.; Howell, A. R. Tetrahedron Lett. 1999, 40, 7051-7054.
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(7) Bekolo, H.; Howell, A. R. New J. Chem. 2001, 25, 673-675.