A-Mesyloxy ketones

This rearrangement can be applied to chiral a-mesyloxy ketones by in situ reduction with DIBAH followed by addition of triethylaluminum or diethylaluminum chloride. The resulting aldehyde is reduced as formed to an optically active 2-aryl- or 2-alkenylpropanol.4 Example ... 

The same methodology was successfnUy applied for the preparation of alkynes 152 and alkenes 153 from a-sulfinyl ketones 150 and S-mesyloxy snlfoxides 151, respectively (equation 52). 

Asymmetricpinacol-type rearrangement. Oiiral P-mesyloxy tertiary alcohols undergo a stereospecific pinacol-type rearrangement in the presence of triethylaluminum (excess) to furnish optically pure a-aryl or a-vinyl ketones (equation I). The reaction is particularly... 

More recently, worlc has been reported showing that silyl enol ethers of ketones, esters and lactones can be efficiently converted to a-sulfonyloxy carbonyl compounds on treatment with either [hydroxy(to-syloxy)iodo]benzene or [hydroxy(mesyloxy)iodo]benzene (equation 23). This method is similar to that used by the same workers to introduce the trifluoromethylsulfonyloxy group a to ketone carbonyl groups via their silyl enol ethers.While the major interest in these developments is the further func-tion zation of the a-position of carbonyl compounds the method clearly offers a route to a. -unsatu-rated species. 

Ai -A-homo-4-ketones by reaction with lithium and biphenyl at The resulting dienone is transformed into the corresponding tropone by treatment with bromine. The Swiss chemists also found that base treatment of 19-mesyloxy-A " -3-oximes gives directly 4-oximino-A-homo-estra-l(10),2,4a-trienes in moderate yield. ... 

Another analogue of HTI which was used with either ketones or silyl enol ethers was [hydroxy(mesyloxy)iodo]benzene, PhI(OH)OS02Me [25]. A related reagent formed in situ from iodosylbenzene and trimethylsilyl triflate, probably PhI(OSiMe3)OTf, reacted similarly with silyl enol ethers to afford a-ketotriflates (see Table 5.3). /1-Diketones and /1-ketoesters underwent tosyloxylation by HTI the reaction was very effective in substrates with a perfluoroalkyl moiety and gave their hydrates [26] ... 

Analog of HTIB. Various derivatives of HTIB with substituents in the iodoarene nucleus, ArI(OH)OTs, and three arenesnlfonyloxy analogs have been reported. [Hydroxy (mesyloxy)Iodo] benzene, PhI(0H)03SMe, and [hydroxy((+)-10-camphorsulfonyloxy)iodo]benzene are also known. [Hydroxy ((bis (pheny loxy) phosphoryl) oxy) iodobenzene], PhI(0H)0P(0)(0Ph)2, shows considerable potential for phosphate ester synthesis. Thus far, the a-oxyphosphorylation of ketones and -dicarbonyl compounds, the oxyphosphoryllac-tonization of alkenoic acids, and the conversion of terminal alkynes to monoketol phosphates with HPIB have been reported. 

---