Performic acid hydroxylation with

The same corynoline analog (214) was obtained more conveniently through photolysis in the presence of nitrosobenzene. Addition of nitrosobenzene to 208 from the opposite side of the methyl group resulted in the B/C-trans adduct 215. Reduction of 215 with sodium borohydride followed by acidic treatment gave the B/C-cis product 217 via 216. Hydroxylation of 217 with performic acid and hydrogenolysis of the diol 218 completed the synthesis of 214 (126). 

Hydrazines of type 89 react with various carbonic acid derivatives to furnish cyclized product. Under basic conditions (KOH), in the presence of carbon disulfide or arylisothiocyanates, the cyclized thione 90 is obtained (Scheme 7) <1966JOG3528, 1984JCCS315>. Analogous reactions performed in the absence of base gave 91 as a 3-thiol when performed with carbon disulfide, as a 3-hydroxyl with methyl chloroformate, or as a 3-arylamino with arylisothiocyanates in the presence of dicyclohexylcarbodiimide (Scheme 7) <1986JHC1339, 1992IJB467>. 

Assay of bile acids was an essential tool for the early investigation of the enterohepatic circulation, and proved a focus of attention with the belief that serum bile-acid concentrations would provide a sensitive diagnostic test for liver disease. There are three fundamental assay types, based on enzymatic oxidation of a hydroxyl with linked NAD reduction, chromatographic separations and quantitation, encompassing both gas-liquid and high-performance liquid chromatography, and radioimmunoassay assays. 

Sasaki42 performed trcms-hydroxylation of trcm,y-2-hydroxy-3-pent-enoic acid (89) with 40% peroxyacetie acid, and obtained 5-deoxy-DL-arabinono-l,4-laetone (90) as the sole product. Jary and Kefurt41 repeated this experiment, and found that the reaction was not fully stereospeci-fie besides 90, 5-deoxy-DL-ribono- 1,4-lactone (91) was also formed. Reduction of the mixture of 90 and 91 with lithium aluminum hydride gave the corresponding 5-deoxy-DL-pentitols (92 and 93) in the ratio of 2.8 1. 

It was reported independently by three research groups that MFI-type zeolites selectively catalyze the reaction of N20 with benzene to give phenol C6H6 + N20 —> C6H5OH + N2 [93-96]. Fe/ZSM-5 shows remarkable performance in benzene hydroxylation to phenol with N20 as oxidant, which is the first example of a successful gas phase direct phenol synthesis from benzene [97]. No other catalysts show similar high performances to the Fe/ZSM-5 catalyst. At present, iron is the sole element capable of catalyzing the benzene-to-phenol reaction [98]. Direct oxidation of benzene to phenol by N20 has been commercialized in the so-called AlphOx process in Solutia Inc., US A, where N20 is obtained as a by-product in adipic acid production with nitric acid [97, 99, 100] a selectivity >95% to phenol is achieved at >40% conversion at around 4000 C. But the process is cost-effective only if N20 can be obtained cheaply as a by-product in adipic acid production. 

Since there were variations in the experimental conditions (such as the nature of the aldehyde or the number of performed reaction cycles) it remains possible that the event or the extent of symmetry breaking depend on these. Even if the first reaction cycle gives rise to only a small ee, further ones will certainly amplify this small bias and push it with its proper enantiomeric direction to the edges. Further influence could come from achiral additives. Kawasaki et al. assume in the case of the addition of achiral silica gel that this additive may provide an improved reaction platform by coordination of the aldehyde and involvement of a zinc atom from the reaction of diisopropylzinc with the acidic hydroxyl group of silica gel [40]. Further systematic experimental studies, which can also shed more light on the basic reaction mechanism, are required to better understand the differences in the results. 

The peracid methods invariably open the epoxide with reversion of configuration, i.e. trans-diol formation. Aryl substituents, however, are converted to the cw-diols with retention of configuration.118-120 Olefins which have been hydroxylated by means of in situ percarboxylic acid techniques include cyclohexene (65-73%),121 dodecane (91 %)122 and oleic acid (99%).123 Chlorestrol has been frans-hydroxylated with performic acid in high yield (91%).124... 

On the other hand, the dehydroamine 110 was converted on treatment with performic acid to the 11,12-trans glycol 115, identical to natural 12-hydroxycorynoline (115) (100,101). Hydrogenolytic cleavage of the 12-hydroxyl group of 12-hydroxycorynoline (115) with palladium on carbon afforded corynoline (117) along with the isomeric cis glycol 116 (100,101). 

The acetonide is cleaved under mild acidic conditions with catalytic amounts of / -toluene sulfonic acid, releasing hydroxyl diol 42. Performing the reaction in ethanol leads to an acetal exchange process, whose mechanism is analogous to the THP acetal cleavage presented earlier. 

The presence of a phenyl group on one or both carbon atoms of an olefin alters the situation by causing cleavage of the epoxide ring with retention of configuration at the phenylated carbon atom with production of the c/s-glycol. A recent example reported by Riviere" is that hydroxylation of 1-phenylcycloheptene (1) with performic acid gives the cis-diol (2), identical with the product of hydroxylation with... 

The protein is completely hydrolyzed by acid (6 N HCl, 24 hours or longer at 110°C, under vacuum or inert gas) to its constituent amino acids and the resultant hydrolysate is evaporated to dryness. The amino acid composition is determined on protein hydrolysates obtained after 24,48, and 72 hours of acid treatment. The content of amino acids with bulky aliphatic side chains such as isoleucine, leucine, and valine, which undergo slow hydrolysis, is calculated from an extrapolation of the hydrolysate data to infinite time. The content of hydroxyl-containing amino acids, which are slowly destroyed during hydrolysis, is obtained by a corresponding extrapolation to zero time. Since cysteine, cystine, and methionine residues are somewhat unstable to hydrolysis, these residues are oxidized to cysteic acid and methionine sulfone, respectively, with performic acid before quantitative analysis. Cysteine, or half-cystine, is quantitated as a derivative such as carboxymethyl cysteine after reduction and alkylation, a necessary prerequisite to subsequent sequence analysis. Tryptophan... 

Recently, Sha and Schacht performed a study with gentamicin in guinea pigs and showed that simple iron chelators such as malic acid, tartaric acid, and even dimethyl sulfoxide, can protect these animals from the hearing loss caused by gentamicin [204]. Malic acid and tartaric acid are dicarboxylic acids that can chelate iron, and dimethyl sulfoxide scavenges free radicals such as hydroxyl radical. 

Thiol-to-hydroxyl group transformation has been oxidatively performed on 107 with nitric acid to give 109 (60G1821). A similar result was accomplished by hydrolytic displacement of the thiol group of 108 with an aqueous solution of sodium hydrogen carbonate (60G1830) (Scheme 47). 

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