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This work reports the separation of FTC enantiomers using an amylose tris[( S )-1-phenylethylcarbamate] coated onto APS-Nucleosil (7 μm particle size, 500 A pore size, 20% w/w, 15×0.46 cm ID) chiral column under polar organic elution mode. Good enantioselectivity ( α =1.9) with excellent enantioresolution ( R S =3.3) was achieved by the use of methanol with 0.02% of triethylamine acetate as mobile phase. The method allows the accurate determination of as low as 0.2% of each enantiomer as an impurity. The validated method proved to be reliable and sensitive for the quantification of both enantiomers as impurity in different batches of emtricitabine and β- d -(+)-FTC.

The methoxymethoxy substituent when attached to an aromatic ring functions as a moderately strong ortho-directing group in hydrogen-metal exchange reactions. In many cases the propensity of the methoxymethoxylated arene toward ring metallation is greatly enhanced with concomitant suppression of undesirable side reactions such as nucleophilic attack and addition of the metallating species. Unlike many other ortho-directing groups, the regio-direction of the methoxymethoxy substituent when in conjunction with other weaker directing groups is dependent upon the metalating medium. Thus, by changing the electron donating capacity of the metallating medium it is possible to selectively direct metallation to either of the positions ortho to the methoxymethoxy substituent.

By means of spectral and chemical studies the structure of Grahamimycin A1 1 , a novel macrocyclic dilactone antibiotic from Cytospora, is established.

Stereoselective rearrangement of cis-5-(4-methoxybenzyl)-spiro[5,2]-octan-4-ol cis-1 in acidified THF-90% H 2 O 2 affords 9-oxabicyclo[6.2.1]nonyl hydroperoxides 7 and 8 which are converted to medium-ring, keto-butyrolactones 2 and 3.

Ketones are readily spiroannelated by 2-chloroethyldimethyl sulfonium iodide 1 in the presence of t-butoxide anion in t-butanol. The procedure affords a simple one step -spirocyclopropanation of ketones in good yields.

Rearrangement of spiro[5,2]octan-4-ol, 1, in acidified THF-H2O2 is a selective process in which substitution occurs with retention of configuration and ring-expansion with inversion of the carbinyl center.