Ring closing alkyne metathesis RCAM

Ring-Closing Alkyne Metathesis (RCAM) and Alkyne... 

Fig. 3a,b Typical diyne metathesis reactions ring-closing alkyne metathesis (RCAM, a) diyne cross metathesis (ACM, b)... 

An intersecting RCM is the alkyne variant called ring closing alkyne metathesis (RCAM). In this case, two alkynes, usually methyl terminated, are converted to the cycloalkyne. Unlike RCM, RCAM does not produce geometric isomers. Using this methodology, several constrained diamino-suberic analogues can be produced (Scheme 28.15).45... 

Ring-closing alkyne metathesis (RCAM) leads to alkyne macrocydes in excellent yields [36]. When combined with hydrogenation using a Lindlar-type catalyst, it is a convenient pathway to macrocydic Z-cydoalkenes. Fiirstner and coworkers utilized this strategy for numerous total syntheses of natural products [37], epothilone A being one of them [38]. 

Ring-closing alkyne metathesis (RCAM) and RCM of a diene have been reported for the synthesis of macrocycles. 

The authors proposed an approach where the macrolactone would be formed by a ring closing alkyne metathesis (RCAM) [97] of diyne 161. This RCAM precursor would in turn be obtained by the reunion of the northern fragment 162 and the southern fragment 163, for which a Myers alkylation was envisioned to control one of the stereogenic centers (Scheme 2.75). 

This chapter focuses on one aspect of alkyne metathesis ring-closing alkyne metathesis (RCAM) in natural product synthesis. A brief background precedes an overview of RCAM, the catalyst systems used in RCAM-containing approaches to natural products, and a discussion of its potential as a synthetic strategy. The value... 

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