1119-16-0Relevant articles and documents
-
Williams
, (1955)
-
The desA and desB genes from Clostridium scindens ATCC 35704 encode steroid-17,20-desmolase
Devendran, Saravanan,Mythen, Sean M.,Ridlon, Jason M.
, p. 1005 - 1014 (2018)
Clostridium scindens is a gut microbe capable of removing the side-chain of cortisol, forming 11?-hydroxyandrostenedione. A cortisol-inducible operon (desABCD) was previously identified in C. scindens ATCC 35704 by RNA-Seq. The desC gene was shown to encode a cortisol 20?-hydroxysteroid dehydrogenase (20?-HSDH). The desD encodes a protein annotated as a member of the major facilitator family, predicted to function as a cortisol transporter. The desA and desB genes are annotated as N-terminal and C-terminal transketolases, respectively. We hypothesized that the DesAB forms a complex and has steroid-17,20-desmolase activity. We cloned the desA and desB genes from C. scindens ATCC 35704 in pETDuet for overexpression in Escherichia coli. The purified recombinant DesAB was determined to be a 142 ± 5.4 kDa heterotetramer. We developed an enzyme-linked continuous spectrophotometric assay to quantify steroid- 17,20-desmolase. This was achieved by coupling DesABdependent formation of 11?-hydroxyandrostenedione with the NADPH-dependent reduction of the steroid 17-keto group by a recombinant 17?-HSDH from the filamentous fungus, Cochliobolus lunatus. The pH optimum for the coupled assay was 7.0 and kinetic constants using cortisol as substrate were Km of 4.96 ± 0.57 μM and kcat of 0.87 ± 0.076 min?1. Substrate- specificity studies revealed that rDesAB recognized substrates regardless of 11?-hydroxylation, but had an absolute requirement for 17,21-dihydroxy 20-ketosteroids.- Devendran, S., S. M. Mythen, and J. M. Ridlon. The desA and desB genes from Clostridium scindens ATCC 35704 encode steroid-17,20-desmolase.
An organocatalytic enantioselective direct α-heteroarylation of aldehydes with isoquinoline: N -oxides
Bertuzzi, Giulio,Pecorari, Daniel,Bernardi, Luca,Fochi, Mariafrancesca
, p. 3977 - 3980 (2018)
A new protocol for the enantioselective direct α-heteroarylation of aldehydes with isoquinoline N-oxides, via chiral enamine catalysis, has been successfully developed. High enantiomeric excesses and moderate to good yields were achieved for a variety of α-heteroarylated aldehydes.
Activation of molecular hydrogen in cobalt-catalyzed hydroformylation
Pino, Piero,Major, Arpad,Spindler, Felix,Tannenbaum, Rina,Bor, Gyeorgy,Horvath, Istvan T.
, p. 65 - 76 (1991)
The mechanism of the activation of molecular hydrogen in cobalt-catalyzed hydroformylation of olefins has been studied by high pressure IR spectroscopy using HCo(CO)4 (1) under 100 bar H2 (or D2) in the absence or presence of CO at room temperature.The treatment of 1 with 100 bar H2 resulted in the formation of Co2(CO)8 (2) and a small amount of Co4(CO)12 (3), and the transient formation of HCo3(CO)9 (4).In the reaction of 1 with one equivalent of 3,3-dimethyl-butene-1 under 100 bar H2 both hydrogenation and hydroformylation occur, but the former is much faster.In the presence of large amounts of 1 the predominant path for the hydrogenation of the olefin involves the reaction of two equivalents of 1 with the olefin even under 100 bar of H2.Under a very low partial pressure of CO the stability of 1 is increased and the hydrogenation significant slowed down.The preferred path of the hydroformylation of the olefin involves the addition of H2 and CO from gas phase even in the presence of large amount of HCo(CO)4 (1) under 100 bar H2 and 2.3 bar CO at room temperature.The studies reveal that the mechanism of H2 activation in the presence of HCo(CO)4 (1) is highly dependent on the reaction conditions.Under 100 bar H2 and at rom temperature the activation of molecular hydrogen starts at a coordinatively unsaturated acyl cobalt carbonyl, yielding an aldehyde and an unknown cobalt species.It is believed that this species is a coordinatively unsaturated hydriodo cobalt carbonyl like (HCo(CO)3>, and can activate and catalytically hydroformylate the olefin.
Isotope-Labeling Studies Support the Electrophilic Compound i Iron Active Species, FeO3+, for the Carbon-Carbon Bond Cleavage Reaction of the Cholesterol Side-Chain Cleavage Enzyme, Cytochrome P450 11A1
Yoshimoto, Francis K.,Jung, I-Ji,Goyal, Sandeep,Gonzalez, Eric,Guengerich, F. Peter
, p. 12124 - 12141 (2016)
The enzyme cytochrome P450 11A1 cleaves the C20-C22 carbon-carbon bond of cholesterol to form pregnenolone, the first 21-carbon precursor of all steroid hormones. Various reaction mechanisms are possible for the carbon-carbon bond cleavage step of P450 11A1, and most current proposals involve the oxoferryl active species, Compound I (FeO3+). Compound I can either (i) abstract an O-H hydrogen atom or (ii) be attacked by a nucleophilic hydroxy group of its substrate, 20R,22R-dihydroxycholesterol. The mechanism of this carbon-carbon bond cleavage step was tested using 18O-labeled molecular oxygen and purified P450 11A1. P450 11A1 was incubated with 20R,22R-dihydroxycholesterol in the presence of molecular oxygen (18O2), and coupled assays were used to trap the labile 18O atoms in the enzymatic products (i.e., isocaproaldehyde and pregnenolone). The resulting products were derivatized and the 18O content was analyzed by high-resolution mass spectrometry. P450 11A1 showed no incorporation of an 18O atom into either of its carbon-carbon bond cleavage products, pregnenolone and isocaproaldehyde. The positive control experiments established retention of the carbonyl oxygens in the enzymatic products during the trapping and derivatization processes. These results reveal a mechanism involving an electrophilic Compound I species that reacts with nucleophilic hydroxy groups in the 20R,22R-dihydroxycholesterol intermediate of the P450 11A1 reaction to produce the key steroid pregnenolone.
Method for synthesizing fluorescent dye intermediate aldehyde by hydroformylation of 1,3-diene compound
-
Paragraph 0053-0054; 0056-0057, (2021/08/07)
The invention discloses a method for synthesizing a fluorescent dye intermediate aldehyde by hydroformylation of 1,3-diene compound. The method comprises the following steps: S1, sequentially adding 0.01 mmol (1 mol%) of [Rh(cod)Cl]2, 0.1 mmol of a phosphine ligand(P/Rh=10/1) and 1 mmol of diene into a reaction flask, adding 1 ml of a solvent DMF, putting the reaction flask into a high-pressure reaction kettle, after the reaction is finished, transferring a mixed solution into a 25 mL glass bottle with 200 microliters of n-tridecane as an internal standard by using a rubber head dropper, and detecting; and S2, determining the product yield and the structure through a gas chromatograph and a nuclear magnetic resonance spectrum, wherein the obtained olefin conversion rate is larger than 99%, the aldehyde yield ranges from 61% to 99%, and the regioselectivity of the product aldehyde ranges from 70/30 to 100/0. According to the method disclosed by the invention, the separation and purification steps of aldehyde products are simplified, and the substrate of the dialkene hydroformylation reaction is excellent in universality.
Aluminum(III) Salen Complexes as Active Photoredox Catalysts
Gualandi, Andrea,Marchini, Marianna,Mengozzi, Luca,Kidanu, Hagos Tesfay,Franc, Antoine,Ceroni, Paola,Cozzi, Pier Giorgio
supporting information, p. 1486 - 1490 (2019/11/03)
Metallosalen are privileged complexes that have found important applications in catalysis. In addition, their luminescent properties have also been studied and used for sensing and biological applications. Salen metal complexes can be efficient photosensitizers, but they can also participate to electron transfer processes. Indeed, we have found that commercially available [Al(Salen)Cl] is an efficient photoredox catalyst for the synergistic stereoselective reaction of alkyl aldehydes with different bromo ketones and malonates to give the corresponding enantioenriched α-alkylated derivatives. The reaction was performed in the presence of a MacMillan catalyst. [Al(Salen)Cl] is able to replace ruthenium complexes, showing that also aluminum complexes can be used in promoting photoredox catalytic reactions.
