Polystyryl boronic acid

A very selective and versatile polymer-grafted protective group for 1,2-diols has been described by Frichet et Polystyryl boronic acid 117 (Scheme 3.7.6) reacted selectively with diols to... 

The concept of immobilizing diol compounds with a boronic acid conjugated support as a sort of heterogeneous protecting group strategy is the antipode of the diol-based supports described in Section 1.4.2. Examples of such boronic acid matrices include polystyryl boronic acid resins (120) [500-502], the cellulose-derived support 121 [503], the methacrylic polymer 122 [504], and the polyacrylamide-supported nitroarylben-... 

Full details of the protection of 1,2- and 1,3-diols using the polystyryl boronic acid (63) have been published this year. 

Lithium tetrafluoroborate in wet acetonitrile has been described as an effective combination for the hydrolysis of acetals under mild weakly acidic conditions. Dithians were unaffected. Methods for the hydrolysis of thioacetals continue to appear. Reagents that have been described include a polystyryl-mercury(n) trifluoroacetate combination, which retains the metal on the resin, lead(iv) dioxide and boron trifluoride etherate, aqueous hydrochloric acid in dioxan containing dimethyl sulphoxide, methyl-bis(methylthio)sulphonium hexa-chloroantimonate, and iodoxybenzene, catalysed by toluene-p-sulphonic acid. Dithioacetals derived from ethane-1,2-dithiol may be cleaved with dimethyl sulphoxide in combination with either t-butyl or trimethylsilyl bromides and iodides. Regeneration of ketones from ethanediyl-S S -acetals via the lithium-di-isopropylamide-promoted fragmentation to the thioketone and subsequent hydrolytic work-up only gives satisfactory yields for aryl methylketone derivatives. Dithioacetal SS-dioxides are rapidly cleaved in hot methanolic hydrochloric acid solution. ... 

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