Synthesis and Reactivity of Phosphates from RCM

The preference of cuprate nucleophiles to add to the more sterically accessible olefin of 26 led into examining the possible functionalization of the endocyclic olefin [4a] After regioselective hydrogenation of the exocyclic olefin in the presence of Wilkinson s catalyst, cuprate addition to phosphate 31 preferentially occurred at 

When attempting to undergo CM with type III partners [23], very poor yields were observed in the presence of [Ru]-III (Table 4.1). In accordance with Grubbs 

In 2008, Hanson et al. reported the synthesis of two key subunits of dolabelide C, which possess the anti-1,3-diol motif observed at the C7/C9 positions and the l,3,4-onti,flnti-stereotriad at the C19/C21-C22 positions. Retrosynthetic analysis segmented the 24-membered macrolide into a C1-C14 subunit 38 and 

The synthesis of bicyclic phosphate triester 26 has been accompUshed via a desymmetrization of C2-symmetric diol 24 using a phosphate-tether mediated 

The use of temporary tethers in synthesis represents a powerful approach to the coupling of two advanced structures en route to more advanced synthons. RCM plays a key role in the construction of sultone and phosphate heterocycles providing effective methods where both sulfur and phosphorus serve as temporary tethers mediating several selective transformations. The use of sultones to construct 1,3-dienols possessing an internal Z-olefin has been utilized in the synthesis of the originally proposed structure of ( )-mycothiazole and has the potential of expanding to other biologically active natural products. Phosphate tethers have served a central role in the construction of asymmetric 1,3-antt-diol subunits, which have been demonstrated in the construction of both the C1-C14 and C15-C30 subunits of dolabeHde C [7]. Additional uses of these versatile heterocycles are in order and will be reported in future studies. 

---