Highly Water‐Soluble Carbaborane‐Bridged Bis(glycophosphonates)

Abstract

A facile synthesis of carbaboranediyl-bis(glycophosphonates) and corresponding phosphonothioates is presented. These compounds show extraordinarily high water solubility and low cytotoxicity.

Enantiomerically pure 3-hydroxypropyl diisopropylidene mannose derivatives

“…14 However, the reaction of a mixture of glycosides 3 and 4 with carbaboranylbis-phosphonite 5 promoted by benzimidazoliumtriflate (BIT) 15 followed by oxidation or sulfurization did not yield the corresponding bis-mannosylphosphonate 6 (R = (prot)Gly, Scheme 1). In all cases, 3 and 4 were recovered and only the bis-phosphonic acid derivative of 6 (R = H) was formed during acidic workup and identified by 11 11 Therefore, a short alkylene spacer was introduced between the OH group and the glycoside, as long alkylene spacers would increase the lipophilicity, leading to lower water solubility and higher cytotoxicity. 16 In the case of mannose the alkylation of the anomeric oxygen of a mixture of 3 and 4 would also prevent the formation of the open-chain conformer and should thus allow separation of all four isomers in enantiomerically pure form.…”

Glycoconjugates of polyhedral boron clusters

“…After deprotection of the phosphonate, the isopropylidene groups of the galactose moieties were cleaved with trifluoroacetic acid/water (9:1) and subsequently converted into the desired disodium salts by ion exchange [28]. possessing four galactose moieties were synthesized [29].…”

New developments in the medicinal chemistry of carboranes

“…Tetra-D-galactosylated carboranediyl bis(phosphonates) containing four galactose moieties 53-55 were also synthesized in like manner. However, these were synthesized from a different starting materials possessing four dimethylamido groups 72 . The synthesis of bis(glycophosphonates) and phosphonothioates of metaand para-carboranes as shown in Fig.…”