No abstract

[reaction: see text] Changing the identity of the N leaving group on a hydroxylamine-based reoxidant gives a dramatic improvement to the tethered aminohydroxylation reaction. Using OCOC6F5 as a leaving group means that only 1 mol % of osmium is required and yields as high as 98% can be obtained. Acyclic homoallylic alcohols were substrates considered too unreactive for effective use in the tethered aminohydroxylation reaction; improved reaction conditions mean that they have now become viable substrates for oxidation.

No abstract

The fourth protocol: the rarely studied N-thiopivaloyl group plays a crucial role in mediating efficient α lithiation and incorporation of diverse electrophiles onto an azetidine ring; in the presence of chiral ligands, this chemistry also provides the first example of an enantioselective electrophilic substitution on a four-membered ring.

Alpha-diazo-beta-ketoesters bearing allylic ether functionality undergo highly stereoselective Ru-carbene-catalyzed alkene cross-metathesis followed by Rh(2)(OAc)(4)-catalyzed oxonium ylide formation/[2,3] sigmatropic rearrangement in a one-flask operation and in a highly diastereoselective manner. The methodology has been demonstrated in a concise synthesis of the anti-HIV agent hyperolactone C.