Beta-D-(-)-Arabinose is an important chiral sugar molecule with wide application value. It has important applications in pharmaceutical synthesis, food additives, dehydrating agents, cosmetics and other fields. Therefore, there are various methods to synthesize Beta-D-(-)-Arabinose. This article will mainly introduce some of the main synthetic methods.
Extraction of Beta-D-(-)-Arabinose from natural products:
The method of extracting Beta-D-(-)-Arabinose from natural products is the most direct and can obtain high-purity products. The most common natural source of Beta-D-(-)-Arabinose is xylan, which is a disaccharide composed of D-xylose and D-glucose. Beta-D-(-)-Arabinose is one of the structural units of xylan. Xylan can be found in plant cell walls such as lignin, pine trees that grow in cold regions, etc.
The extraction method of Beta-D-(-)-Arabinose is the same as that of xylan. In general, the acid method is the most commonly used xylan extraction method. A xylan sample is first added to an acidic solution, heated until the sugar monomers are detached from the aggregates, then filtered and washed. After xylan treatment, the Beta-D-(-)-Arabinose contained in the acidic solution can be separated and purified by neutralization and crystallization.
Currently, there are many effective chemical methods available for the synthesis of Beta-D-(-)-Arabinose. Here are a few ways:
1. Glycogen route:
Step 1: Obtain Xylose from Xylan:
The glycogen route synthesis of Beta-D-(-)-Arabinose starts from xylose. Xylose is a six-carbon sugar ubiquitously present in plant cell walls and can be obtained by hydrolyzing xylan (usually extracted from plants).
Xylan plus H2O → Xylose plus other sugars
Xylan is a polysaccharide composed of multiple xylose molecules and is usually a colorless or brown powdery substance. The hydrolysis reaction needs to be catalyzed by an acid or an enzyme, and an acid catalyst is usually used for the hydrolysis reaction. After hydrolysis, xylose can be used to synthesize Beta-D-(-)-Arabinose.
Step 2: Convert xylose to L-arabinose:
The conversion of xylose to L-arabinose is a key step in the synthesis of Beta-D-(-)-Arabinose via the glycogen route. This process requires the use of a set of enzymes to catalyze a series of reactions that convert xylose to arabinose.
First, xylose is converted into D-xylose ketose through catalytic reaction.
Xylose plus ATP → D-xylose ketose plus ADP
Secondly, D-xylose ketose will be transformed into L-xylose ketose through isomerization reaction.
D-xylose ketulose → L-xylose ketulose
Then, the reaction catalyzed by L-xylose glusidase was subjected to Cooper cyclization to obtain L-arabino-deoxy-hex-2-ulonate.
L-xylose ketose → L-arabinuronic acid
Finally, under the action of arabinuronic acid, use NADPH and glucosidase to reduce arabinuronic acid to L-arabinose.
L-arabinuronic acid plus NADPH plus H plus → L-arabinose plus NADP plus
The third step: convert L-arabinose to Beta-D-(-)-Arabinose:
The conversion of L-arabinose to Beta-D-(-)-Arabinose requires a set of enzymes to catalyze the reaction.
First, L-arabinose is phosphorylated to form arabinose-6-phosphate.
L-arabinose plus ATP → arabinose-6-phosphate plus ADP
Then, a hydrolysis reaction converts arabinose-6-phosphate to Beta-D-(-)-Arabinose-5-phosphate (Beta-D-(-)-arabinose-5-phosphate).
Arabinose-6-phosphate plus H2O → Beta-D-(-)-arabinose-5-phosphate
Finally, Beta-D-(-)-arabinose-5-phosphate undergoes dephosphorylation to form Beta-D-(-)-Arabinose.
Beta-D-(-)-arabinose-5-phosphate → Beta-D-(-)-arabinose plus Pi
The glycogen route synthesis of Beta-D-(-)-Arabinose starts from xylose. First, xylose is obtained from xylan, then xylose is converted to L-arabinose, and finally L-arabinose is converted to Beta-D-(-)-Arabinose. This process requires the use of multiple enzyme-catalyzed reactions, each of which is critical. Through this synthesis method, highly efficient, economical and pure Beta-D-(-)-Arabinose can be obtained, which provides a solid foundation for its application in the fields of biology, medicine and chemical synthesis.
2. Knight's reaction:
The method, developed in the 1940s, requires polychlorinated aromatic hydrocarbons as the starting material. In the Knight reaction, polychlorinated aromatic hydrocarbons are reacted with a mixture of acid and detergent, and then Obenzyl-D-arabinose is added together with the mixture. After a series of steps, Beta-D-(-)-Arabinose is synthesized.
Step 1: To prepare Beta-D-(-)-Arabinose, we need to prepare Beta-D-(-)-Arabinose sugar and pre-added reagents first, and oxygenation is one of the most common manufacturing methods. It consists of two stages: first, methyl-D-glucofuranoside undergoes aromatization reaction in the presence of iodine salt to obtain 4,6-O-methyl anisole derivatives; then aromatizes at the 5-O-angle position Structured reaction, and then reduced to obtain Beta-D-(-)-Arabinose.
Step 2: Prepare the reagents and solvents required for the Knight reaction. It is necessary to prepare a bottle of solution containing 30ml of 50 percent acetic acid and 10g of Beta-D-(-)-Arabinose sugar, and proceed to the subsequent steps on this basis.
Step 3: Add sulfuric acid as an acid catalyst. Before adding the acidic catalyst, 100 ml of ethanol should be added to the test tube, followed by 0.1 ml of concentrated sulfuric acid.
Step 4: Add boric acid under cooling condition. After the solvent system was cooled to room temperature, 150 ml of isopropanol was added, and then 0.1 ml of boric acid was added, and stirred gently.
Step five: Reaction heating. Heat in a constant temperature oil bath for about 40 to 50 minutes to completely react the aldose in the solution to produce a sugar enol ester product.
Step 6: Catalytic hydrogenation. After the reaction was complete, the test tube was taken out from the oil bath and allowed to cool down to room temperature. Then add 1 milliliter of n-heptane and 0.05 milliliter of sodium tungstate solution to carry out catalytic hydrogenation reaction, often have to wait for several days.
Schritt 7: Extrahieren Sie das Produkt. Das Produkt wurde durch Eintauchen aus der Lösung extrahiert und das Produkt wurde durch Methoden wie Ultraviolettspektroskopie, Infrarotspektroskopie und Kernspinresonanz identifiziert und charakterisiert, und die Struktur des Reaktionsprodukts wurde abgeleitet.
3. Glycosidation reaction:
This method is also very popular, and its raw material is D-xyloside. First, react D-xyloside and methanol under the action of a catalyst to obtain Obenzyl-D-arabinose. Next, Obenzyl-D-arabinose is reacted with oxidized NaIO4 in the presence of the substrate, followed by addition of dry quaternary ammonium salts, thereby obtaining Beta-D-(-)-Arabinose.
In a word, Beta-D-(-)-Arabinose can be synthesized by several methods mentioned above, each method has its advantages and disadvantages, and different methods can be selected according to different actual needs.