Committed to preserving our shared environment – further details available on request.
Can be used in processes in compliance with cGMP standards.
Manufacture of consumables is accredited by the world renowned British Standards Institute.
Flexible supply chains, back up manufacturing and warehousing ensures supply risk reduction
Can be used in processes in compliance with GLP standards.
Products which are scaleable from lab or development to process scale.
Long to indefinite product shelf life, reduced process risk.
Supports pharma guidelines for reducing elemental impurities in APIs.
Further extractable information provided on request.
Raw materials certified free of materials of human or animal origin.
Chemical substances used in our manufacturing process do not require registration.
Able to withstand mechanical stirring and heating under normal reaction conditions.
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Sodium triacetoxyborohydride has emerged as one of the reagents used most frequently for carrying out reductive amination of carbonyl compounds, a reaction that is also known as reductive alkylation of amines. This reagent has gained preference relative to other reducing agents as a result of its mild reaction conditions and broad scope of reactivity. The typical conditions for reductive amination reactions with sodium triacetoxyborohydride utilize 1.5–2.0 equivalents of reagent in THF or dichloroethane (DCE) in the presence of acetic acid. A disadvantage of sodium triacetoxyborohydride is its poor solubility, and that product isolation requires an aqueous quench followed by liquid-liquid extraction and column chromatography.
Biotage® MP-Triacetoxyborohydride is a macroporous polystyrene-supported equivalent of tetraalkylammonium triacetoxyborohydride. MP-Triacetoxyborohydride has primary applications in the reductive amination of aldehydes and ketones under neutral or mildly acidic reaction conditions. This resin was developed to perform in a manner similar to that of the well-established sodium triacetoxyborohydride, while simplifying reagent handling and product purification. Moreover, for many of these reactions, a scavenger resin may be added for one-pot purification of the product.
MP-Triacetoxyborohydride offers scope and reactivity similar to that of sodium triacetoxyborohydride with the additional convenience of a polymer-supported reagent for handling and purification. Typical conditions require 2.5 equivalents of resin relative to the limiting reagent in THF. Acetic acid is not required (Scheme 2).
After the reaction is complete, a scavenger resin may be added for product purification. For example, in the case of reductive alkylation using an excess of primary amine, PS-Benzaldehyde may be used to scavenge the excess starting primary amine from the product secondary amine. Likewise, in the case of reductive alkylation of secondary amines, an excess of the starting secondary amine may be scavenged by PS-Isocyanate. The product is then isolated by simply filtering off the resins. Catch-and-release of the amines with MP-TsOH or ISOLUTE® SCX-2 may also be employed to purify the reductive amination products when an excess of carbonyl compounds is used.
Capacity and Stability
The triacetoxyborohydride content of the resin is determined by hydrolyzing the resin with aqueous HCl (1 M). The capacity is calculated based on the amount of liberated hydrogen gas collected. The resin typically contains approximately 10% THF (as calculated from the 1H NMR spectrum of a CDCl3 extraction of the resin). The THF is required to stabilize the resin and it is important not to remove this by drying in vacuo. The resin is stable for at least 12 months at 4 ˚C in a closed container. Storage of samples for multiple months at room temperature does not affect the resin.
Reductive Alkylation of Primary Amines
A THF solution (0.50 M) of N-(3-aminopropyl)morpholine (1.2 mL, 0.60 mmol) was added to a THF solution (0.50 M) of 1,4-cyclohexanedione mono-ethylene ketal (1.0 mL, 0.50 mmol). MP-Triacetoxyborohydride (2.0 mmol/g, 0.625 g, 1.25 mmol) was then added and the mixture was agitated for 16 h at room temperature. When the reaction was complete, PS-Benzaldehyde (0.42 g, 0.5 mmol) and THF (2 mL) were added and the mixture was further agitated for 6 h. The resin was filtered and washed with THF (2 x 4 mL). The combined solution was concentrated to afford the product secondary amine as the acetate salt in 77% yield and 100% purity. The secondary amine was characterized by gas chromatography and 1H NMR.
For further information please see product note PPS391.