Mucocin
26 April 2006
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Crimmins, Zhang and Diaz. Org. Let., 2006, ASAP. DOI: 10.1021/ol060704z
Ruthenium-tastic total synthesis of the polyether Mucocin, using three metathesis reactions in this paper. Most interesting was the creation of the central THF as a 2,5-DHF via a Hoye-type activation strategy. This involves using a allyloxymethyl side chain to direct the Ru complex insertion, resulting in preferential formation of the 5-member ring.
Coupling of this fragment to the right-hand piece proceeded via a efficient Sonogashira coupling and subsequent diimide reduction, whilst the left-hand section was inserted via metathesis, in a similar fashion to Mootoo’s synthesis.
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please use your photoshop magic to show sp2-sp2 relationship.
Done, sorry about that…
thanks.
i’m wondering if they tried de-TES (free allylic hydroxy group is known to suppress the reactivity of Grubbs I) substrate with Grubbs I (without activating -allyloxymethyl- tether, of course). that might bring some selectivities of 5- over 6- membered ring formation (with some side product, i guess).
nevertheless i’m all in favor of the application of relay-RCM (activation strategy):
1. selectivity doesn’t come from suppression of reactivity (e.g., allylic alcohol i mentioned above, some of asymmetric reactions)
2. just cool and elegant (of course, two more steps to deal with)