Relay ring-closing metathesis

Wallace DJ. Relay ring-closing metathesis—a strategy for achiev- 127. ing reactivity and selectivity in metathesis chemistry. Angew. 

Dudley and co-workers used a relay ring-closing metathesis strategy in the synthesis of (+)-dihydro-e/ /-deoxyarteannuin B, a key biogenic... 

Percy and co-workers applied a similar strategy in the synthesis of a trisubstituted cyclooctene derivative in an effort to determine the limits of relay ring-closing metathesis.Reaction of diene 315 (R = H) in the presence of 4 (three additions 10 mol %, then 5 mol % then 5 mol % over a 12-day period) and Ti(Oi-Pr)4 in refluxing dichloromethane furnished the corresponding octocycle 316 in only 24% yield. However, when a relay approach was employed, diene 317 (R = (CH2)3CHCH3) gave the... 

For reactions with more hindered termini, Hoye has developed the relay ring-closing metathesis (RRCM) approach, where a specially designed triene is used as the precursor (e.g. Scheme 2.13). ° The initial RCM step yields an intermediate carbene in which the ruthenium catalyst has been delivered to a hindered site by virtue of the intramolecular nature of the reaction this carbene then performs the desired RCM reaction. The throw-away fragment is typically a volatile unit, such as dihydro-furan or cyclopentene, although DEDAM-type units have also been utdized. ... 

Hoye TR, Jeffrey CS, Tennakoon MA, Wang J, Zhao H. Relay Ring-Closing Metathesis (RRCM) A Strategy for Directing Metal Movement Throughout Olefin Metathesis Sequences. J Am Chem Soc. 2004 126(33) 10210-10211. 

Hoye TR, Jeon J, Tennakoon MA. AUyknalonate as an Activator Subunit for the Initiation of Relay Ring-Closing Metathesis Reactions. Angew Chem Int Ed. 2011 50(9) 2141-2143. 

Ashworth IW, Miles JAL, Nelson DJ, Percy JM, Singh K. Trisubstituted cyclooctene synthesis at the limits of relay ring-closing metathesis a racemic difluorinated analogue of fucose. Tetrahedron. 2009 65(46) 9637—9646. 

Hoye s laboratory has pirmeered in the field of relay alkene metathesis. In 2004, Hoye and coworkers showed the first example of using relay ring closing metathesis (RRCM) for the synthesis of tetrasubstituted alkene (49) (Fig. 15) [58]. 

Wang X, Bowman EJ, Bowman BJ, Porco JA Jr. Total synthesis of the salicylate enamide macroUde oximidine HI application of relay ring-closing metathesis. Angew. Ghent. Int. Ed. 2004 43 3601-3605. 

Hoye TR, Jeon J, Kopel, LC, Ryba TD, Tennakoon MA, Wang Y. Total synthesis of peloruside A through kinetic lac-toiuzation and relay ring-closing metathesis cyclization reactions. Angew. Chem. Int. Ed. 2010 49 6151-6155. 

RCM (1 to 2, Scheme 9.1) is one of the most common and important types of olefin metathesis reaction. Accommodation of considerable structural complexity within A in RCM substrates 1 is one of the hallmarks of this powerful and broadly applicable reaction. Nonetheless and despite significant advantages available by modification of external factors (for example, catalyst selection, additive use, solvent choice, or ethylene concentration), not every diene substrate 1 can be successfully cychzed to cycloaUcene 2. Because of the advent of relay ring-closing metathesis (RRCM, 4a to 4b to 3 to 2, Scheme 9.1), chemists now have an alternative for resuscitating/redirecting these otherwise lifeless/recalcitrant systems when such a limitation is encountered. 

Jeffrey, C.S. (2004) Master thesis. Part I The epoxidation of 1.0 mg of geraniol. Part 11 Relay ring closing metathesis (RRCM) Selectivity in tandem enyne synthesis. University of Minnesota, Minneapolis, MN. 

This type of metathesis cascade can be considered as an example of relay ring-closing metathesis (RRCM) (Chapter 9) [10]. This methodology is classically used in RCM of... 

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