Silyl Ketene Imines

Silyl ketene imines (SKIs) are a wide variety of nucleophiles possessing a pair of orthogonal substituents within a cumulene group and can have other functional groups, including alkenes, allenes, ketenes, and amines. SKIs can be employed in a wide range of reactions involving C–C bond formation and/or the formation of stereogenic centers.

When combined with an appropriate catalyst and ligand, C–C bond forming reactions with SKIs are highly stereo­selective. SKIs can be converted into nitriles which are precursors of many other functional groups including carboxylic acids, amines, and aldehydes.[2] One of the first synthetic applications of SKIs was described in 1987: a Diels–Alder [4+2] cycloaddition stating a versatile method to obtain anilines and cyclohexanones, leading to a range of aromatic amines in 52–89% yield.[3]

Due to their geometry and the presence of two orthogonal substituents, SKIs have proven to be excellent nucleophiles in order to obtain stereogenic centers.[4]

• References

• 1 Denmark SE, Wilson TW. Synlett 2010; 1723
• 2 Denmark SE, Wilson TW. Nature Chem. 2010; 2: 937
• 3 Differding E, Vandevelde O, Roekens B, Van T T, Ghosez L. Tetrahedron Lett. 1987; 28: 397
• 4 Denmark SE, Wilson TW. Angew. Chem. Int. Ed. 2012; 51: 9980
• 5 Watt DS. J. Org. Chem. 1974; 39: 27990
• 6 Zhao J, Liu X, Luo W, Xie M, Lin L, Feng X. Angew. Chem. Int. Ed. 2013; 52: 3473
• 7 Denmark SE, Wilson TW, Burk MT, Heemstra JR. J. Am. Chem. Soc. 2007; 129: 14864
• 8 Long S, Panunzio M, Qin W, Bongini A, Monari M. Eur. J. Org. Chem. 2013; 5127
• 9 Vu JM. B, Leighton JL. Org. Lett. 2011; 13: 4056
• 10 Notte GT, Vu JM. B, Leighton JL. Org. Lett. 2011; 13: 816
• 11 Guin J, Varseev G, List B. J. Am. Chem. Soc. 2013; 135: 2100
• 12 Denmark SE, Wilson TW. Angew. Chem. Int. Ed. 2012; 51: 3236
• 13 Mermerian AH, Fu GC. Angew. Chem. Int. Ed. 2005; 44: 949