Diethylaminosulfur trifluoride

Description

Diethylaminosulfur trifluoride (DAST) is a nucleophilic fluorinating agent with wide use in organic chemistry. Deoxo-Fluor is more thermally stable alternative to DAST.

Chemical properties

Pale yellow liquid. Soluble in most non-polar organic solvents, commonly used in CH2Cl2, CHCl3 and CCl4.

The Uses of Diethylaminosulfur trifluoride

Diethylaminosulfur Trifluoride is a very useful Nucleophilic fluorinating agent in chemical synthesis. It is also used as a reagent in the preparation of 2-thiazolines from (1,2)-thioam ido-alcohols.

The Uses of Diethylaminosulfur trifluoride

To a solution of the SM (3.3 g, 32.3 mmol) in DCM (100 mL) at -78 C under N2 was added DAST (13.0 mL, 96.9 mmol). The reaction mixture was stirred at -78 C for 1 h, then at RT for 1 h. The reaction mixture was then slowly poured into sat aq NaHCO3 (200 mL) at 0 C. The mixture was extracted with DCM (2 x 60 mL). The combined organics were dried (Na2SO4) and concentrated. The residue was purified by silica gel column chromatography (10:1 PE/EtOAc) to provide the product as a colorless oil. [2.2 g, 65%]

What are the applications of Application

Diethylaminosulfur trifluoride (DAST) is used as a precursor to prepare 2,6-dimethoxybenzoyl fluoride and 2-thiazolines. It is a useful fluorinating agent used for a variety of compounds including alcohols, thioethers, alkenols and cyanohydrins. It also serves as a catalyst for Friedel-Crafts allylation reaction using tertiary cyclopropyl silyl ethers and in the rearrangement of homoallylic alcohols to unsaturated aldehydes. It plays an important role for gem difluorination of ketopipecolinic acids.