Biobutanol production from coffee silverskin

BACKGROUND

Coffee silverskin, a by-product from coffee roasting industries, was evaluated as a feedstock for biobutanol production by acetone-butanol-ethanol fermentation. This lignocellulosic biomass contained approximately 30% total carbohydrates and 30% lignin. Coffee silverskin was subjected to autohydrolysis at 170 °C during 20 min, with a biomass-to-solvent ratio of 20%, and a subsequent enzymatic hydrolysis with commercial enzymes in order to release simple sugars. The fermentability of the hydrolysate was assessed with four solventogenic strains from the genus Clostridium. In addition, fermentation conditions were optimised via response surface methodology to improve butanol concentration in the final broth.

RESULTS

The coffee silverskin hydrolysate contained 34.39 ± 2.61 g/L total sugars, which represents a sugar recovery of 34 ± 3%. It was verified that this hydrolysate was fermentable without the need of any detoxification method and that C. beijerinckii CECT 508 was the most efficient strain for butanol production, attaining final values of 4.14 ± 0.21 g/L acetone, 7.02 ± 0.27 g/L butanol and 0.25 ± 0.01 g/L ethanol, consuming 76.5 ± 0.8% sugars and reaching a butanol yield of 0.269 ± 0.008 gB/gS under optimal conditions.

CONCLUSIONS

Coffee silverskin could be an adequate feedstock for butanol production in biorefineries. When working with complex matrices like lignocellulosic biomass, it is essential to select an adequate bacterial strain and to optimize its fermentation conditions (such as pH, temperature or CaCO3 concentration).

Enhanced butanol production by solvent tolerance Clostridium acetobutylicum SE25 from cassava flour in a fibrous bed bioreactor

To enhance the butanol productivity and reduce the material cost, acetone, butanol, and ethanol fermentation by Clostridium acetobutylicum SE25 was investigated using batch, repeated-batch and continuous cultures in a fibrous bed bioreactor, where cassava flour was used as the substrate. With periodical nutrient supplementation, stable butanol production was maintained for about 360h in a 6-cycle repeated-batch fermentation with an average butanol productivity of 0.28g/L/h and butanol yield of 0.32g/g-starch. In addition, the highest butanol productivity of 0.63g/L/h and butanol yield of 0.36g/g-starch were achieved when the dilution rate were investigated in continuous production of acetone, butanol, and ethanol using a fibrous bed bioreactor, which were 231.6% and 28.6% higher than those of the free-cell fermentation. On the other hand, this study also successfully comfirmed that the biofilm can provide an effective protection for the microbial cells which are growing in stressful environment.

Synthesis of 2-Butanol by Selective Hydrogenolysis of 1,4-Anhydroerythritol over Molybdenum Oxide-Modified Rhodium-Supported Silica

Rh-MoOx /SiO2 (Mo/Rh=0.13) is an effective catalyst for the hydrogenolysis of 1,4-anhydroerythritol (1,4-AHERY) and provides 2-BuOH in high yield of 51 %. This is the first report of the production of 2-BuOH from 1,4-AHERY by hydrogenolysis. 1,4-AHERY was more suitable as a starting material than erythritol because the 2-BuOH yield from erythritol was low (34 %). Based on the kinetics and comparison of reactivities of the related compounds using Rh-MoOx /SiO2 and Rh/SiO2 catalysts, the modification of Rh/SiO2 with MoOx leads to the high activity and high selectivity to 2-BuOH because of the generation of reactive hydride species and the strong adsorption of 1,4-AHERY on MoOx species. The reaction proceeds by main two routes, (I) the combination of single C-O hydrogenolysis with the desorption of intermediates, a usual route in hydrogenolysis, and (II) multiple C-O hydrogenolysis without the desorption of intermediates from the active site, and the reaction mechanism for Route (II) is proposed.

Techno-economics of carbon preserving butanol production using a combined fermentative and catalytic approach

This paper presents a novel process for n-butanol production which combines a fermentation consuming carbon dioxide (succinic acid fermentation) with subsequent catalytic reduction steps to add hydrogen to form butanol. Process simulations in Aspen Plus have been the basis for the techno-economic analyses performed. The overall economy for the novel process cannot be justified, as production of succinic acid by fermentation is too costly. Though, succinic acid price is expected to drop drastically in a near future. By fully integrating the succinic acid fermentation with the catalytic conversion the need for costly recovery operations could be reduced. The hybrid process would need 22% less raw material than the butanol fermentation at a succinic acid fermentation yield of 0.7g/g substrate. Additionally, a carbon dioxide fixation of up to 13ktonnes could be achieved at a plant with an annual butanol production of 10ktonnes.

Optimization of butanol production from tropical maize stalk juice by fermentation with Clostridium beijerinckii NCIMB 8052

Mixed sugars from tropical maize stalk juice were used to carry out butanol fermentation with Clostridium beijerinckii NCIMB 8052. Batch experiments employing central composite design (CCD) and response surface methodology (RSM) optimization were performed to evaluate effects of three factors, i.e. pH, initial total sugar concentration, and agitation rate on butanol production. Optimum conditions of pH 6.7, sugar concentration 42.2g/L and agitation rate 48 rpm were predicted, under which a maximum butanol yield of 0.27 g/g-sugar was estimated. Further experiments demonstrated that higher agitation facilitated acetone production, leading to lower butanol selectivity in total acetone-butanol-ethanol (ABE). While glucose and fructose are more preferable by C. beijerinckii, sucrose can also be easily degraded by the microorganism. This study indicated that RSM is a useful approach for optimizing operational conditions for butanol production, and demonstrated that tropical maize, with high yield of biomass and stalk sugars, is a promising biofuel crop.

An analysis of net energy production and feedstock availability for biobutanol and bioethanol

In this study, the potential of biobutanol was evaluated as an alternative to bioethanol which is currently the predominant liquid biofuel in the US. Life-cycle assessments (LCAs) suggest that the net energy generated during corn-to-biobutanol conversion is 6.53 MJ/L, which is greater than that of the corn-derived bioethanol (0.40 MJ/L). Additionally, replacing corn with lignocellulosic materials in bioethanol production can further increase the net energy to 15.90 MJ/L. Therefore, it was interesting to study the possibility of using domestically produced switchgrass, hybrid poplar, corn stover, and wheat straw as feedstocks to produce liquid biofuels in the US. By sustainable harvest based on current yields, these materials can be converted to 8.27 billion gallons of biobutanol replacing 7.55 billion gallons of gasoline annually. To further expand the scale, significant crop yield increases and appropriate land use changes are considered two major requirements.

Strain improvement and process development for biobutanol production

Among various renewable and sustainable energy sources being explored, biobutanol has been recognized as one of the promising alternatives for biofuels due to its attractive physical and chemical properties. Various inventions have been reported for the biological production of butanol, maintaining its competitiveness in efficiency, economy, and production scale. This article reviews such patented inventions and relevant research achievements to the microbial strains and fermentation processes for the enhanced production of biobutanol. We also discuss current challenges for strain improvement based on recent developments.

Synthesis and enantioselective rearrangement of (Z)-4-triphenylmethoxy-2,3-epoxybutan-1-ol enantiomers

Efficient enzyme catalyzed kinetic resolutions of a synthetically useful chiral building block, (Z)-4-triphenylmethoxy-2,3-epoxybutan-1-ol, are reported. The highest selectivities were achieved by Lipozyme TL IM and Amano Lipase PS enzymes in the presence of vinyl acetate. Enantiomeric enrichment of the optically active acetate isomer was accomplished by selective crystallization of the racemic part of the enantiomeric mixture. Enzyme catalyzed hydrolysis of the acetate also provided an optically pure epoxybutanol derivative. O-Benzylation of (+)-(Z)-1-hydroxy-4-triphenylmethoxy-2,3-epoxybutane followed by super base promoted diastereo- and enantio-selective rearrangement resulted in (+)-(2R,3R,1'R)-3-[1-hydroxy-2-(triphenylmethoxy)ethyl]-2-phenyloxetane in >98% ee and de. Configurations of the new optically active products were determined by chemical correlation.

(R)- and (S)-4-TIPS-3-butyn-2-ol. Useful Precursors of Chiral Allenylzinc and Indium Reagents

A convenient route to the enantiomers of 4-TIPS-3-butyn-2-ol of >95% enantiomeric purity by reduction of the ynone precursor 4 with the Noyori N-tosyl-1,2-diphenylethylenediamineruthenium cymene catalyst is described. The mesylate derivative of the (S) enantiomer (1c) is converted in situ to an allenylzinc or indium reagent in the presence of a catalyst derived from Pd(OAc)2 and Ph3P and either Et2Zn or InI. A second in situ addition of these reagents to aldehydes leads to anti homopropargylic alcohol adducts. The additions proceed in generally high (60-90%) yield with modest to excellent diastereoselectivity and high enantioselectivity. Only slight mismatching (<5%) is observed with chiral alpha-methyl and alpha-silyloxy aldehydes. Additions to alpha-substituted enals are highly diastereoselective, while beta,beta-disubstituted enals afford ca. 2:1 mixtures of anti and syn adducts.

Synthesis of (2R,3S) 3-amino-4-mercapto-2-butanol, a threonine analogue for covalent inhibition of sortases

L-Threonine 2 was converted in seven steps into the protected aminomercaptoalcohol 8, a threonine mimic. This compound 8 was coupled to various oligopeptides to produce two different tetrapeptide analogues, for example, 11 and 17, which were shown to inhibit the Sortase enzymes (SrtA and SrtB) via covalent attachment of the thiol groups of 11 and 17 to the catalytically active cysteine residue of the Sortase enzymes.

Synthesis of a Versatile (S)-3-(Hydroxymethyl)butane-1,2,4-triol Building Block and its Application for the Stereoselective Synthesis of N-Homoceramides

[structures: see text] A versatile (S)-3-(hydroxymethyl)butane-1,2,4-triol building block has been synthesized starting from D-isoascorbic acid, a common food preservative. The key transformation in this approach was the introduction of branching through a high yield and fully regioselective epoxide opening. This flexible synthon has been elaborated to a new class of (dihydro-)N-homo(phyto)ceramides.

Synthesis and biodistribution of [11C]R116301, a promising PET ligand for central NK1 receptors

N1-(2,6-Dimethylphenyl)-2-(4-{(2R,4S)-2-benzyl-1-[3,5-di(trifluoromethyl)[carbonyl-(11)C]benzoyl]hexahydro-4-pyridinyl}piperazino)acetamide ([(11)C]R116301) was prepared and evaluated as a potential positron emission tomography (PET) ligand for investigation of central neurokinin(1) (NK(1)) receptors. 1-Bromo-3,5-di(trifluoromethyl)benzene was converted in three steps into 3,5-di(trifluoromethyl)[carbonyl-(11)C]benzoyl chloride, which was reacted with N1-(2,6-dimethylphenyl)-2-{4-[(2R,4S)-2-benzylhexahydro-4-pyridinyl]piperazino}acetamide providing [(11)C]R116301 in 45-57% decay-corrected radiochemical yield. The total synthesis time, from end of bombardment (EOB) to the formulated product, was 35 min. Specific activity (SA) was 82-172 GBq/micromol (n=10) at the end of synthesis. N1-([4-(3)H]-2,6-Dimethylphenyl)-2-(4-{(2R,4S)-2-benzyl-1-[3,5-di(trifluoromethyl)benzoyl]hexahydro-4-pyridinyl}piperazino)acetamide ([(3)H]R116301) was also synthesized (SA: 467 GBq/mmol). The B(max) for [(3)H]R116301 measured in vitro on Chinese hamster ovary cell membranes stably transfected with the human NK(1) receptor was 19.10+/-1.02 pmol/mg protein with an apparent dissociation constant of 0.08+/-0.01 nM. Ex vivo, in vivo and in vitro autoradiography studies with [(3)H]R116301 in gerbils demonstrated a preferential accumulation of the radioactivity in the striatum, olfactory tubercule, olfactory bulb and locus coeruleus. In vivo, the biodistribution of [(11)C]R116301 in gerbils revealed that the highest initial uptake is in the lung, followed by the liver and kidney. In the brain, maximum accumulation was found in the olfactory tubercules (1.10+/-0.08 injected dose (ID)/g 20 min post injection (p.i.)) and the nucleus accumbens (1.00+/-0.12ID/g 10 min p.i.). Tissue/cerebellum concentration ratios for striatum and nucleus accumbens increased with time due to rapid uptake followed by a slow wash out (1.29 and 1.64, respectively, 30 min p.i.). A tissue to cerebellum ratio of 1.33 and 1.62 was also observed for olfactory bulb and olfactory tubercules, respectively (20 min p.i.). In summary, [(11)C]R116301 appears to be a promising radioligand suitable for the visualization of NK(1) receptors in vivo using PET.

Chirality and Fragrance Chemistry: Stereoisomers of the Commercial Chiral Odorants Muguesia and Pamplefleur

[structure: see text] The work describes the enzyme-mediated preparation and the odor evaluation of the single stereoisomers of the commercial odorants Muguesia and Pamplefleur. The synthetic approach to Muguesia stereoisomers helped to clear the assignment of the relative configuration of intermediate diols 5. The odor response of Pamplefleur isomers was found to be rather unusual. No stereoisomer prevailed, but each one played a definite role in establishing the odor sensation of the final blend.

tert-Buyldiphenylsilylethyl (“TBDPSE”): A Practical Protecting Group for Phenols

[reaction: see text] A new protection group for phenols, the 2-(tert-butyldiphenylsilyl)ethyl (TBDPSE) group, has been prepared and investigated. Protection of a variety of substituted phenols proceeds in good to excellent yield. The group is stable to mild acid, base, hydrogenolysis conditions, and lithium/halogen exchange on the protected phenol. Removal is achieved with strong acid or standard fluoride treatment.

Palladium-Catalyzed Ring Expansion Reaction of (Z)-1-(1,3-Butadienyl)cyclobutanols with Aryl Iodides. Stereospecific Synthesis of (Z)-2-(3-Aryl-1-propenyl)cyclopentanones

[reaction: see text] A novel type of cascade ring expansion process has been developed by the palladium-catalyzed reaction of (Z)-1-(1,3-butadienyl)cyclobutanols with aryl iodides. The reaction proceeds in a stereospecific manner to produce (Z)-2-(3-aryl-1-propenyl)cyclopentanones. It has also been found that regioselective alpha-arylation of alkenyl cyclopentanones proceeds to afford the alpha-arylated cyclopentanones.

Incorporation of Lipophilic Drugs in Sugar Glasses by Lyophilization using a Mixture of Water and Tertiary Butyl Alcohol as Solvent

In this study, a new and robust method was evaluated to prepare physically stable solid dispersions. Trehalose, sucrose, and two inulins having different chain lengths were used as carrier. Diazepam, nifedipine, Delta(9)-tetrahydrocannabinol, and cyclosporine A were used as model drugs. The sugar was dissolved in water and the drug in tertiary butyl alcohol (TBA). The two solutions were mixed in a 4/6 TBA/water volume ratio and subsequently freeze dried. Diazepam could be incorporated at drug loads up to 63% w/w. DSC measurements showed that, except in some sucrose dispersions, 97-100% of the diazepam was amorphous. In sucrose dispersions with high drug loads, about 10% of the diazepam had crystallised. After 60 days of exposure at 20 degrees C and 45% relative humidity (RH), diazepam remained fully amorphous in inulin dispersions, whereas in trehalose and sucrose crystallization of diazepam occurred. The excellent physical stability of inulin containing solid dispersions can be attributed to the high glass transition temperature (T(g)) of inulin. For the other drugs similar results were obtained. The residual amount of the low toxic TBA was only 0.1-0.5% w/w after freeze drying and exposure to 45% RH and 20 degrees C. Therefore, residual TBA will not cause any toxicity problems. This study provides a versatile technique, to produce solid dispersions. Inulin glasses are preferred because they provide an excellent physical stability of the incorporated amorphous lipophilic drugs.

Lipase mediated chiral resolution of 4-arylthio-2-butanol as an intermediate for β-lactam antibiotics

This paper deals with chiral enzymatic resolution of 4-arylthio-2-butanols by lipase to prepare potential intermediates of beta-lactam antibiotics. Among several lipases employed, lipase P type enzyme gave the highest ee value to prepare (R)-4-arylthio-2-butyl acetate. The enzymatic resolution of phenyl substituted alcohol (6a) using lipase P showed the highest ee value (99.7%) among those of 4-arylthio-2-butanol derivatives. Lipase P mediated hydrolysis of acylester 7a gave also (R)-alcohol 6a selectively. For determination of enantiomeric purity of these enzymatic resolved analytes, liquid chromatographic analysis was performed using two coupled Chiralcel OD and (R,R)-WhelkO chiral column.

Microbial Synthesis of the Energetic Material Precursor 1,2,4-Butanetriol

The lack of a route to precursor 1,2,4-butanetriol that is amenable to large-scale synthesis has impeded substitution of 1,2,4-butanetriol trinitrate for nitroglycerin. To identify an alternative to the current commercial synthesis of racemic d,l-1,2,4-butanetriol involving NaBH4 reduction of esterified d,l-malic acid, microbial syntheses of d- and l-1,2,4-butanetriol have been established. These microbial syntheses rely on the creation of biosynthetic pathways that do not exist in nature. Oxidation of d-xylose by Pseudomonas fragi provides d-xylonic acid in 70% yield. Escherichia coli DH5alpha/pWN6.186A then catalyzes the conversion of d-xylonic acid into d-1,2,4-butanetriol in 25% yield. P. fragi is also used to oxidize l-arabinose to a mixture of l-arabino-1,4-lactone and l-arabinonic acid in 54% overall yield. After hydrolysis of the lactone, l-arabinonic acid is converted to l-1,2,4-butanetriol in 35% yield using E. coli BL21(DE3)/pWN6.222A. As a catalytic route to 1,2,4-butanetriol, microbial synthesis avoids the high H2 pressures and elevated temperatures required by catalytic hydrogenation of malic acid.

Synthesis and characterization of water-soluble hydroxybutenyl cyclomaltooligosaccharides (cyclodextrins)

We have examined the synthesis of hydroxybutenyl cyclomaltooligosaccharides (cyclodextrins) and the ability of these cyclodextrin ethers to form guest-host complexes with guest molecules. The hydroxybutenyl cyclodextrin ethers were prepared by a base-catalyzed reaction of 3,4-epoxy-1-butene with the parent cyclodextrins in an aqueous medium. Reaction byproducts were removed by nanofiltration before the hydroxybutenyl cyclodextrins were isolated by co-evaporation of water-EtOH. Hydroxybutenyl cyclodextrins containing no unsubstituted parent cyclodextrin typically have a degree of substitution of 2-4 and a molar substitution of 4-7. These hydroxybutenyl cyclodextrins are randomly substituted, amorphous solids. The hydroxybutenyl cyclodextrin ethers were found to be highly water soluble. Complexes of HBen-beta-CD with glibenclamide and ibuprofen were prepared and isolated. In both cases, the guest content of the complexes was large, and a significant increase in the solubility of the free drug was observed. Dissolution of the complexes in pH 1.4 water was very rapid, and significant increases in the solubility of the free drugs were observed. Significantly, after reaching equilibrium concentration, a decrease in the drug concentration over time was not observed.

Synthesis and biological activity of the structural analogues of (-)-cabenegrin A-I

A series of phenylbutene and butanol derivatives (6a-j, 12, 13, 15, 17, 24b,c, 26, 27a,b) were prepared from the readily available resorcinol derivatives 2a-f and 7-hydroxy-chroman (18). The products were tested for inhibitory activity on the LPS-induced TNF-alpha production in the plasma in comparison with that of cabenegrin A-I (1a).

4-Dialkylamino-1-(5-substituted or unsubstituted 1-phenyl-1H-pyrazol-4-yl)butan-1-ols: synthesis and evaluation of analgesic, anti-inflammatory and platelet anti-aggregating activities

A number of 4-dialkylamino-1-(5-substituted or unsubstituted 1-phenyl-1H-pyrazol-4-yl)butan-1-ols 2a-n were synthesized and tested in vivo for anti-inflammatory and analgesic activities and in vitro for platelet anti-aggregating activity. Dimethylaminoderivatives 2b, e, g showed good analgesic activity; almost all of them had strong platelet anti-aggregating properties at a final concentration of 1 x 10(-3) M; pyrazoles 2c, d, f-h showed weak anti-inflammatory activity.

Synthesis and antifungal activities of (2R,3R)-2-aryl-1-azolyl-3-(substituted amino)-2-butanol derivatives as topical antifungal agents

2-Aryl-1-azolyl-3-(substituted amino)-2-butanol derivatives I were prepared by ring-opening reaction of epoxides II with excess amine, and their antifungal activities were evaluated as topical agents. Azolyl-cyclic amine derivatives with a methylene group showed extremely strong activity with a broad spectrum in vitro. In general, anti-Trichophyton mentagrophytes activities of most of the topical antifungal agents are substantially reduced by addition of keratin (a major constituent of the keratinized tissue). However, the triazole derivative (2R,3R)-2-(2,4-difluorophenyl)-3-(4-methylenepiperidino)-1-(1H-1,2 ,4- triazol-1-yl)-2-butanol ((-)-40, KP-103) showed very little deactivation by addition of keratin. This biological characteristic of triazole derivative (-)-40 resulted in excellent therapeutic efficacy on dermatophytosis superior to that of the corresponding imidazole derivative ((-)-41).

Symmetry-based inhibitors of HIV-1 protease. Design, synthesis and preliminary structure-activity studies of acylated 2,3-diamino-1-hydroxypropanes and 2,4 diamino-1-hydroxybutanes

Two series of peptidomimetics containing a novel C(2) pseudosymmetrical hydroxyalkyldiamino core structure were prepared from amino acid starting materials and tested for inhibitory activity against the HIV-1 protease (HIV-1 Pr) and the virus in cell culture. In the 2,3-diamino-1-hydroxypropane series, compound 6a, containing P1/P1(I) benzyl and P2/P2(I) Fmoc substituents, displayed modest HIV-1 Pr inhibition (IC(50) = 430 nM). The corresponding 2,4-diamino-1-hydroxybutane derivative (6b) was the best inhibitor of the series (IC(50) = 160 nM). Interestingly, 6a and 6b showed satisfactory inhibition of HIV replication in cell culture (ED(50) = 340 and 110 nM, respectively), a result which suggests good cell membrane penetration by this class of compounds.

Enzymatic synthesis of unsaturated fatty acid glucoside esters for dermo-cosmetic applications

Unsaturated fatty acid alpha-butylglucoside esters were prepared by enzymatic esterification of alpha-butylglucoside in nonaqueous media. Conditions were firstly optimized using oleic acid as acyl group. Synthesis was possible in several solvents but the presence of water co-product in the medium limited the reaction to a thermodynamic equilibrium corresponding to a maximal conversion yield of 62%. In pure molten substrates, the removal of water under reduced pressure enabled yields superior to 95% to be obtained. Product profiles depended on enzyme origin : whatever the support, immobilized lipase B from Candida antarctica proved to be far more regioselective for the primary hydroxyl group of glucose than immobilized lipase from Rhizomucor miehei. Results obtained could be easily transposed to the acylation of alpha-butylglucoside with a commercial mixture of unsaturated fatty acids containing more than 60% of linoleic acid. The biocatalyst could be recycled more than ten times without any significant activity loss.

Optically active antifungal azoles. IV. Synthesis and antifungal activity of (2R,3R)-3-azolyl-2-(substituted phenyl)-1-(1H-1,2,4-triazol-1-yl)-2-butanols

(2R,3R)-3-Azolyl-2-(substituted phenyl)-1-(1H-1,2,4-triazol-1-yl)-2-butanols (III) were prepared from (2R,3S)-3-methyl-2-(substituted phenyl)-2-(1H-1,2,4-triazol-1-yl)methyloxiranes (21a-f) by a ring-opening reaction with 1H-1,2,3-triazole and 1H-tetrazole and evaluated for antifungal activity against Candida albicans in vitro and in vivo. The optically active oxiranes (21a--f) which serve as the key synthetic intermediates, were synthesized from 1-[(2R)-2-(3,4,5,6-tetrahydro-2H-pyran-2-yl)oxypropanoyl]morpholin e (24) and substituted phenylmagnesium bromide (23) via six steps in a stereocontrolled manner. The 3-(1H-1,2,3,-triazol-1-yl)-(IIIa) and 3-(2H-2-tetrazolyl)-2-butanol (IIId) derivatives showed strong protective effects against candidosis in mice.

Optically active antifungal azoles. V. Synthesis and antifungal activity of stereoisomers of 3-azolyl-2-(substituted phenyl)-1-(1H-1,2,4-triazol-1-yl)-2- butanols

The (2S,3S)-, (2R,3S)- and (2S,3R)-stereoisomers of (2R,3R)-3-azolyl-2-(substituted phenyl)-1-(1H-1,2,4-triazol-1-yl)-2-butanols [(2R,3R)-1a--d] were prepared and evaluated for antifungal activity against Candida albicans in vitro and in vivo to clarify the relationships between stereochemistry and biological activities. The results revealed that the in vitro antifungal activity in each set of the four stereoisomers [(2R,3R)-, (2S,3S)-, (2R,3S)- and (2S,3R)-1a--d] definitely paralleled the in vivo antifungal activity against candidosis in mice, and the order of potency was (2R,3R) >> (2R,3S) > or = (2S,3S) > or = (2S,3R). In addition, the four stereoisomers in each set were assessed for sterol biosynthesis-inhibitory activities in C. albicans and rat liver. The (2R,3R)-isomer was found to exert a strong and selective inhibitory effect on the sterol synthesis in C. albicans as compared with that in rat liver.

Synthesis and enantiomeric purity determination of chiral 3-benzylglycidol, a key synthon for HIV protease inhibitors

The detailed synthesis of (2R,3R)-3-benzylglycidol by the Sharpless asymmetric epoxidation route is described. The enantiomeric purity determination of this compound is complicated by the presence of small quantities of the diastereometric (2R,3S)-3-benzylglycidol from the asymmetric epoxidation of the cis-allylic alcohol, and the unreacted allylic alcohols that are not removed in the product isolation steps. We have developed a direct chiral HPLC method that can resolve all these components for the precise determination of enantiomeric excesses of chiral 3-benzylglycidols.

[1-amino-2-butanols derivates with antiarrhythmic effect]

R(-), R, S, S(+)-1-N-theophylline-7-acetyl or ethyl/-amino-2-butanols were obtained in the reaction of 7-methoxycarbonylmethyltheophylline or 7-beta-chloroethyltheophylline with R(-), R, S, S(+) 1-amino-2-butanols. Compounds I and II tested for antiarrhythmic and hypotensive activity were inactive.

[Synthesis of 1-N-aryloacetamidobutanol derivatives with anti-seizure effect]

New derivatives of 1-N-aryloacetamidobutanols were obtained in the reaction of arylalkylcarboxylic acid chlorides with R, S, R(-), S(+) 1-amino-2-butanols. Structures of the obtained compounds have been confirmed by elemental analysis and IR-spectrometry. Results of pharmacological studies will be published elsewhere.

Preparation of oxygen-15 butanol for positron tomography

Butanol was labeled with 15O using the reaction of tri-n-butyl borane with oxygen gas. The carrier-added synthesis and purification was accomplished in 4 min from the end of bombardment. The efficiency of radiolabel incorporation was 50%. The procedure described will produce [15O]butanol in an amount and quality sufficient for positron tomographic use. This compound is immediately useful for blood flow measurement based upon previous validation of butanol labeled with other radionuclides for that purpose.

Beta-adrenergic blocking agents. 21. threo-1-(Aryloxy)-3-(alkylamino)butan-2-ols

The synthesis and structure-activity relationships of a series of threo-1-(aryloxy)-3-(alkylamino)butan-2-ols are discussed. These compounds are less potent beta-adrenoreceptor antagonists than the corresponding 1-(aryloxy)-3-(alkylamino)propan-2-ols. The data presented indicate that, unlike the arylethanolamine series, substitution of an alkyl group on the carbon atom alpha to the amino function on the oxypropanolamine side chain does not necessarily lead to enhanced vascular (beta 2) selectivity.

Synthesis of diastereoisomeric 4-dimethylamino-3-phenyl-2-butanols and related esters for antimicrobial evaluation

4-Dimethylamino-3-phenyl-2-butanone was reduced to the corresponding diastereoisomeric alcohols, which were separated by fractional crystallization of the corresponding hydrochloride salts. The configuration of the diastereoisomeric alcohols was determined by PMR spectroscopy. The assignments were confirmed by a consideration of the mass spectral data obtained for the two alcohols. Acylation of the alcohols gave the corresponding esters. Antimicrobial evaluation of the compounds prepared showed that 4-dimethylamino-3-phenyl-2-butanone had a promising level of antifungal activity while the other derivatives showed either a low level of potency or were inactive.

[Formation of alcohols during sucrose heating with amino acids]

The formation of alcohols during sucrose heating with amino acids was investigated. The sucrose heating to 180-190 degrees C resulted in the formation of methanol and ethanol and its heating with alanine--propanol and isobutanol. The sucrose heating with phenylalanine led to the formation of beta-phenylethanol as well. Alcohols were identified as benzoates by paper chromatography. They were also identified by infrared spectra.

Actions of some esters of 3,3-dimethylbutan-1-ol (the carbon analogue of choline) on the guinea-pig ileum

1 Estimates were made of the affinity constants for postganglionic acetylcholine receptors of the guinea-pig ileum of the esters of 3,3-dimethylbutan-1-ol with benzilic, (+/-)-cyclohexylphenylglycollic, (+/-)-mandelic, and diphenylacetic acids.2 Attempts were made to check the competitive nature of the antagonism by using as wide a range of concentrations of antagonist as possible, consistent with their limited solubility, and by testing some of the compunds in the presence of a known competitive antagonist.3 By comparing the affinities with those of the corresponding quaternary nitrogen compounds, the contribution made by the positive charge in the onium group to the binding by receptors may be assessed and has been found to be variable. The carbon analogue of benziloylcholine has about one-tenth of its affinity, that of (+/-)-cyclohexylphenylglycolloylcholine has only about one-sixtieth of its affinity, but that of (+/-)-mandelylcholine has slightly higher affinity than that of (+/-)-mandelylcholine itself.4 3,3-Dimethylbutylacetate appeared to be a partial agonist with an affinity constant of about 2.6 x 10(3). The contribution made by the positive charge to the binding of acetylcholine at these receptors therefore seems likely to lie within the range observed with antagonists and there is no reason to believe that there is necessarily greater intimacy of association by agonists than by antagonists.5 Although the C-C and /#/N-C bonds in -CMe(3) and -/#/NMe(3) are similar in length, the groups do not occupy the same volume in solution in water.