(Diethylamino)sulfur Trifluoride

• Catalog: OFC38078090-2
• CAS: 38078-09-0
• Category: Nucleophilic Fluorination Agents
• Synonyms: DAST; Sulfur Trifluoride Diethylamine Complex
• Purity: >90.0%(T)
• MDL Number: MFCD00000363

• IUPAC Name: N-ethyl-N-(trifluoro-lambda4-sulfanyl)ethanamine
• InChI: InChI=1S/C4H10F3NS/c1-3-8(4-2)9(5,6)7/h3-4H2,1-2H3
• InChI Key: CSJLBAMHHLJAAS-UHFFFAOYSA-N
• Isomeric SMILES: CCN(CC)S(F)(F)F
• EC Number: 253-771-2
• Reaxys Registry Number: 1849066

• Molecular Formula: C4H10F3NS
• Molecular Weight: 161.19
• Boiling Point: 32 °C (10 mmHg)
• Flash Point: 23 °C
• Density: 1.22 g/mL at 25 °C(lit.)
• Refractive Index: 1.41-1.416
• Appearance: Colorless to yellow to orange clear liquid
• Storage: 0-10° C; Store under inert gas
• Stability: Moisture sensitive; Heat sensitive

• XLogP3-AA: 3.5
• Hydrogen Bond Donor Count: 0
• Hydrogen Bond Acceptor Count: 5
• Rotatable Bond Count: 2
• Exact Mass: 161.04860498 g/mol
• Monoisotopic Mass: 161.04860498 g/mol
• Topological Polar Surface Area: 4.2Ų
• Heavy Atom Count: 9
• Formal Charge: 0
• Complexity: 78.4

• HS Number: 2921.19.6190

Case Study

(Diethylamino)sulfur Trifluoride for the Oxidation of Benzylic Alcohols and Amines to Carbonyl Compounds

Smeyne D, et al. Synthetic Communications, 2024, 54(18), 1620-1628

A concise and efficient oxidation protocol employing (Diethylamino)sulfur trifluoride (DAST) was developed for the selective transformation of benzylic alcohols and benzylamines into their corresponding carbonyl derivatives. In this method, commercially available DAST was used in combination with dimethyl sulfoxide (DMSO) as both solvent and co-oxidant. The reaction was conducted under mild conditions, with the temperature gradually increased from 0 °C to room temperature over a period of 6 hours. An aqueous workup was applied post-reaction to isolate the products. This strategy demonstrated broad substrate compatibility, tolerating diverse substituents on the aromatic ring, including alkyl, halide, trifluoromethyl, nitro, and methoxy groups. The method efficiently converted primary and secondary benzylic alcohols and amines into aldehydes and ketones, achieving isolated yields ranging from 58% to 91%.

(Diethylamino)sulfur Trifluoride for the Synthesis of Difluoroalkylpyrrolic Compounds

Wang J, et al. Tetrahedron Letters, 1995, 36(14), 2389-2392.

(Diethylamino)sulfur trifluoride (DAST) was employed as a key fluorinating reagent for the synthesis of novel difluoroalkylpyrrolic compounds via its reaction with N-protected acylpyrroles. In this protocol, a series of N-H protected acylpyrroles (3a-3e) were synthesized according to established methods and subsequently reacted with DAST under controlled thermal conditions. Specifically, each acylpyrrole (10 mmol) was treated with DAST (0.26 mL, 20 mmol) at 90 °C until complete consumption of the starting material, as monitored by TLC. Upon completion, the mixture was cooled and extracted with dichloromethane (50 mL), followed by sequential washes with saturated aqueous NaHCO₃ and water (each 50 mL). The organic layer was dried over anhydrous MgSO₄, and the solvent was removed under reduced pressure. Final purification of the crude product was achieved through recrystallization or silica gel chromatography, yielding difluoroalkylpyrrole products (4a-4e) in good to excellent yields. Importantly, the presence of N-protecting groups such as tosyl (-Tos) or benzoyl (-COPh) was found to be critical to the success of the reaction; absence of protection led to decomposition and formation of intractable byproducts. Furthermore, the protecting groups could be cleanly removed using either acid or base, as demonstrated by the hydrolysis of 4a with 2 N NaOH to yield the deprotected compound 5 without fluorine loss.