Kinugasa reaction, intramolecular

A synthetic route to p-lactam-fused enediynes by intramolecular Kinugasa reaction has been successfully developed. The method has widened the scope of the Kinugasa reaction in the synthesis of sensitive systems like tricycle 193 (Scheme 69) [100]. 

On account of their very important biological activity, /9-lactams are important synthetic targets [4-9]. Fused polycyclic -lactam subunits appear in many natural products such as penicillins [4-6] and trinems/tribac-tams [10-13]. Fu et al. reported that such frameworks can be prepared with high levels of enantioselectivity via the intramolecular Kinugasa reaction [ 14, 15] of alkyne-nitrone in the presence of a planar chiral Cu/phosphaferrocene-oxazoline catalyst [16]. For instance, compound 1 was transformed into tricyclic /9-lactam 3 in good stereoselectivity and yielded (88% ee and 74% yield) using 5 mol % of CuBr and 5.5 mol % of complex 2 (Scheme 1). 

Pal, R. and Basak, A. (2006) A novel synthesis of -lactam fused cyclic enediynes by intramolecular Kinugasa reaction. Journal of the Chemical Society, Chemical Communications, (15), 2992-2994. 

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