Ring-Closing Metathesis

Aldrich ChemFiles 2009,9.6, 5.

Ring-closing metathesis has become an essential tool for C-C bond formation as demonstrated by the profound impact on total synthesis in recent years.¹ The first examples date back to 1980 and involved the use of tungsten-based catalysts for the preparation of macrocycles from dialkenyl keto-esters and dialkenyl ketones (Villemin and Tsuji, respectively).² In 1993, Grubbs and coworkers reported the first example of a carbocyclization using a functional-group tolerant molybdenum-based carbene catalyst (silyl ethers, esters, alcohols, and benzyl ethers were all tolerated).³ The Grubbs group subsequently synthesized a new air-stable ruthenium-carbene complex which was able to catalyze the cyclization of a variety of dienes in good yields (Scheme 1).⁴ Numerous research groups have since used RCM to synthesize highly complex molecules. What follows is a brief overview highlighting a few representative examples of RCM. 

Scheme 1

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Materials

References

1. Nicolaou, K. C. et al. Angew. Chem., Int. Ed. 2005, 44, 4490.
2. (a) Villemin, D. Tetrahedron Lett. 1980, 21, 1715. (b) Tsuji, J. et al. Tetrahedron Lett. 1980, 21, 2955.
3. Fu, G. C. et al. J. Am. Chem. Soc. 1993, 115, 3800.
4. Fu, G. C. et al. J. Am. Chem. Soc. 1993, 115, 9856.

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