Silyl ethers sodium periodate

Epoxidadon of (Z)-vinyl sulfone, which is available from the Peterson olefination of (S)-O-pentylideneglyceraldehyde and phenyl trimethylsilylmethyl sulfone in three steps (40% overall yield), with f-BuOOH/t-BuOK in THE gives epoxy sulfone (eq 2). Deprotection of the ketal group and recrystallization affords an optically pure epoxy diol, which is then treated with sodium periodate followed by sodium borohydride to give an alcohol. Protection of the resulting alcohol as its silyl ether yields l/ ,25)-l-phenylsulfonyl-2- [ fcrf-butyldiphenyl)silyl]oxymethyl oxirane ). Its enantiomer is available in the same manner starting from / )-isopropylideneglyceraldehyde. ... 

Overhand, Overkleeft and their collaborators have synthesised a variety of SAAs [39]. The synthesis of Fmoc-protected 6 ( Fig. 2) is illustrated in Scheme 2 [15]. Tri-O-acetyl-D-glu-cal was converted into the SAA precursor 43 in five steps. Formation of the trichloroacetimi-date derivative 44 and a subsequent Overman rearrangement was used to introduce the amino group onto the pyran scaffold giving 45. Hydrogenation of the olefin in 45 was accompanied by cleavage of the silyl ether to afford the primary alcohol which was oxidised with a catalytic amount of ruthenium (III) chloride in the presence of sodium periodate giving 46. Subjection... 

Sulfenylation of lithium enolates with PhS-SPh or of silyl enol ethers with PhS-Cl allows any a-PhS carbonyl compound to be made regioselectively, e.g. 149 and 152 from 147 (see chapter 5). Oxidation with sodium periodate gives the sulfoxide without over-oxidation to the sulfone, but elimination requires reasonably high temperatures (about 120 °C for MeSO but only about 50 °C for PhSO). Together with the unpleasant by-products, the results of disproportionation of unstable PhSOH, this has led to a preference for the selenium version of the reaction, though we must admit that the by-products are even more offensive.22... 

Tetroses and Pentoses - 4-0- -Butyldimethylsilyl-2,3-0-isopropylidene-L-threose (1) has been prepared in seven efficient steps from o-xylose. 3,4-0-Isopropylidene-D-eythrulose (4) has been synthesized from the known tetritol derivative 2 by primary protection as the silyl ether 3, followed by Dess-Martin oxidation and desilylation. Compound 2 was derived from D-isoascorbic acid (see Vol. 22, p. 178, refs. 9,10). In a similar reaction sequence, the enantiomer 5 has been obtained from L-ascorbic acid. The dehomologation of several di-0-isopropylidenehexofuranoses e.g., 6- 7) has been carried out in two steps without intermediate purification, by successive treatment with periodic acid in ethyl acetate, followed by sodium borohydride in ethanol. Selective reduction of 3-deoxy-D-g/jcero-pentos-2-ulose (8) to 3-deoxy-D-g/> cero-pent-2-ose (9) has been achieved enzymically with aldose reductase and NADPH." 4-Isopropyl-2-oxazolin-5-one (10) is a masked formaldehyde equivalent that is easily converted to an anion and demasked by mild acid hydrolysis. One of the three examples of its use in the synthesis of monosaccharides is shown in Scheme 1. ... 

---