The enantioselective 1,3-dipolar cycloaddition reaction (1,3-DCR) which can serve as useful synthetic building blocks is a useful way to synthesize a variety of chiral heterocycles. 1 However, of the propargyl anion type 1,3-dipoles, catalytic asymmetric 1,3-DCR is under-developed, such as nitrile imines. 2 Spirooxindoles functionalized core structures represent an attractive synthetic target due to the biological activity and physical property. 3 A new 1,3-dipolar cycloaddition of nitrile imines with 3-alkenyl-oxindoles was established by a new chiral Mg(ClO4)2 complex of an N ,N’-dioxide ligand. The reaction is so far the sole catalytic synthesis of spiro-pyrazoline-oxindole derivatives. A wide variety of substrates were explored with good yields (up to 98%) and excellent enantioselectivities (up to 99%) obtained. This cycloaddition reaction expands the scope of propargyl anion type 1,3-dipole in the construction of 2-pyrazoline subunit. 4 (1) For reviews of 1,3-dipolar cycloadditions, see: (a) Kanemasa, S. Synlett 2002, 1371. (b) Nájera, C.; Sansano, J. M.Curr. Org. Chem. 2003, 7, 1105. For reviews of asymmetric 1,3-dipolar cycloadditions, see: (c) Gothelf, K. V.; Jørgensen, K. A. Chem. Rev. 1998, 98, 863. (d) Pellissier, H. Tetrahedron 2007, 63, 3235. (e) Stanley, L. M.; Sibi, M. P. Chem. Rev. 2008, 108, 8. (f) Kissane, M.; Maguire, A. R. Chem. Soc. Rev. 2010, 39, 845. (2) For recent examples of reactions with nitrile imine, see: (a) Molteni, G. Heterocycles 2005, 65, 2513. (b) Broggini, G.; DeMarchi, I.; Martinelli, M.; Paladino, G.; Pilati, T.; Terraneo, A. Synthesis 2005, 13, 2246. (c) Buttero, P. D.; Molteni, G.; Pilati, T. Tetrahedron 2005, 61, 2413. (d) Singh, A.; Loomer, A. L.; Roth, G. P. Org. Lett. 2012, 14, 5266. (3) For reviews, see: (a) Galliford, C. V.; Scheidt, K. A. Angew. Chem., Int. Ed. 2007, 46, 8748. (b) Trost, B. M.; Brennan, M. K. Synthesis 2009, 3003. (c) Ball-Jones, N. R.; Badillo, J. J.; Franz, A. K. Org. Biomol. Chem. 2012, 10, 5165. (d) Singh, G. S.; Desta, Z. Y. Chem. Rev. 2012, 112, 6104. (e) Dalpozzo, R.; Bartoli, G.; Bencivenni, G. Chem. Soc. Rev. 2012, 41, 7247. (4) Wang, G.; Liu, X. H.; Huang, T. Y.; Kuang, Y. L.; Lin, L. L.; Feng, X. M. Org. Lett. 2013, 15, 76.

Asymmetric catalytic 1,3-dipolar cycloaddition reaction of nitrile imines for the synthesis of chiral spiro-pyrazoline-oxindoles

251st National Meeting (2016)

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