Bishydroxamic acid

The syntheses of the methyl esters 116-118 from 115 and hydroxamic acids 119-121 were carried out via a typical alkylation of the hydroxy function of methyl 4-hydroxyben-zoate 116 followed by either reaction with hydroxylamine to provide bishydroxamic acids 119-121 containing an alkyl spacer between two aromatic rings. 

These chiral bishydroxamic acids 235a and 235b were synthesized starting from a readily available diamine tartrate salt as shown in Scheme 101. 

A catalytic asymmetric oxidation of mono-, di-, and tri-substituted alkenes using a chiral bishydroxamic acid (BHA) complex of molybdenum catalyst in air at room temperature leads to good to excellent selectivity. It has been suggested that the Mo-BHA complex combines with the achiral oxidant to oxidize the alkene in a concerted fashion by transfer of oxygen from the metal peroxide to the alkene.78 The chiral BHA-molybdenum complex has been used for the catalytic asymmetric oxidation of sulfides and disulfides, utilizing 1 equiv. of alkyl peroxide, with yields up to 83% and ees up to 86%. An extension of the methodology combines the asymmetric oxidation with kinetic resolution providing excellent enantioselectivity (ee = 92-99%).79... 

A vanadium complex with C2-symmetric bishydroxamic acids catalyses the epox-idation of allylic alcohols with ees up to 97% and excellent yields. The catalysts have been used for kinetic resolution of secondary allylic alcohols with high ee. The structure of a possible intermediate has been suggested.38... 

Inhibition of HDACs is one key mechanism to reactivate the expression of these misregulated genes. The astounding tumor specificity of many HDAC inhibitors relays the potential for many of these new compounds for the treatment of cancer and perhaps other disorders. There are five classes of HDAC inhibitors (reviewed in Refs. 51 and 52) including (i) short-chain fatty adds such as sodium- -butyrate (ii) hydroxyamic acids, such as trichostatin A (TSA), suberoylanilide hydroxamic add (SAHA), m-carboxycinnamic acid bishydroxamic acid (CBHA), azelaic bishydroxamic acid (ABHA), and... 

Hydroxyamic acids m-Carboxy cinnamic acid bishydroxamic acid (CBHA) Apoptosis, differentiation, and cell cycle arrest... 

Novel chiral vanadium-bishydroxamic acid complexes have been used to catalyze the enantioselective epoxidation of homoallylic alcohols <2007JA286>. Yields and enantioselectivities are excellent. 

Other metal-based epoxidation catalysts have been explored to overcome some of the hmitations of the Sharpless procedure. One drawback with the Sharpless asymmetric epoxidation is the slightly lower ees often obtained when using cis-olefin substrates. The group of Yamamoto have achieved highly enantioselective epoxidations of ds-alkenes using vanadium(V) oxytriisopropoxide in the presence of C2-symmetric bishydroxamic acid ligands such as (4.23). In contrast to the Sharpless procedure this process is not hampered by the presence of air or... 

Barlan AU, Baak A, Yamamoto H (2006) Enantioselective oxidation of olefins catalyzed by a chiral bishydroxamic acid complex of molybdenum. Angew Chem Int Ed 45 5849-5852... 

Asymmetric epoxidation of both t-allylic and homoallylic alcohols by MgO, catalysed by Hf(IV)-bishydroxamic acid (BHA) where Hf = Hf((yBu)4, results in epoxides with high enantioselectivity. The flexible nature of the Hf(IV)-BHA system is demonstrated." ... 

Enantioselective epoxidations (ee < 98%) of A-alkenyl sulfonamides and IV-tosyl imines have been catalysed by chiral Hf(IV)-bishydroxamic acid complexes. (S)... 

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