Allenoates have been proven to be synthetically useful building blocks providing access to a range of cyclic structures.1 Using cinchona alkaloids as a catalyst allenoates can undergo a formal [4+2] cycloaddition with electron deficient enones.2 In this work, 1 trifluoromethylated enones and 2 methyl-1-trifluoromethylenones were investigated broadening the substitution pattern of the dihydropyran scaffold obtained. Dihydropyran products were obtained in moderate to high yields (up to 81%) and with good stereocontrol (up to 95% ee). Hydrogenation of these dihydropyrans was performed selectively with high yields (up to 93%) and good selectivities (up to 88% de), giving a range of medicinally relevant structures.3 1 a) J. Ye, S. Ma; Acc. Chem. Res. 47, 989 (2014), b) C. Aubert, L. Fensterbank, P. Garcia, M. Malacria, A. Simonneau; Chem. Rev. 111, 1954 (2011), c) Z. Wang, X. Xu, O. Kwon; Chem. Soc. Rev. 43, 2927 (2014). 2 For previous work in this area see: a) C. K. Pei, Y. Jiang, M. Shi; Organic and Biomolecular Chemistry 10, 4355 (2012), b) C. K. Pei, Y. Jiang, Y. Wei, M. Shi; Angew. Chem. Int. Ed. 51, 11328 (2012), c) X. Wang, T. Fang, X. Tong; Angew. Chem. Int. Ed. 50, (2011), d) K. D. Ashtekar, R. J. Staples, B. Borhan; Org. Lett. 13, 5732 (2011). 3 a) C. B. Kelly, M. A. Mercadante, N. E. Leadbeater; Chem. Commun. 49, 11133 (2013), b) M. Jagodzinska, F. Huguenot, G. Candiani, M. Zanda; ChemMedChem 4, 49 (2009), c) S. Purser, P. R. Moore, S. Swallow, V. Gouverneur; Chem. Soc. Rev. 37, 320 (2008)

Cinchona alkaloid-catalyzed formal [4+2] cycloaddition of allenoates and α,β-unsaturated trifluoromethylketones

250th National Meeting (2015)

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