1,4-Bis(bromomagnesio)butane

Abstract

[23708-48-7] C4H8Br2Mg2 (MW 264.53) InChI = 1S/C4H8.2BrH.2Mg/c1-3-4-2;;;;/h1-4H2;2*1H;;/q;;;2*+1/p-2 InChIKey = OMQMAXADYGBHEG-UHFFFAOYSA-L (constructing block agent: transformation of many functional groups into cyclopentane, spiro[4.4]nonane, and spiro[4.5]decane synthetic intermediates, and metallacycles) Solubility: sol THF, ether, and toluene. Form Supplied in: generally prepared in THF. Analysis of Reagent Purity: titration.2 Preparative Method: the following preparative method was found to be of general use for the preparation of various 1,n-bis(bromomagnesio)alkanes (n = 4–6), as well as for primary, secondary, and unsaturated di-Grignard reagents, from the corresponding dibromides.3 1,4-Dibromobutane (69 mmol) dissolved in anhydrous THF (150 mL) is added dropwise to Magnesium turnings (150 mmol) covered with a few mL of the dibromide solution. The exothermic reaction starts within a few minutes and is controlled by the rate of addition of the dibromide, avoiding excessive heating. After an additional 2 to 6 h period, the formation of the reagent is completed (yield ∼90%) (eq 1). However, for 1,3-bis(bromomagnesio)propane, this procedure is not suitable, as the elimination product is mostly formed. Therefore, one should refer to the appropriate literature for that particular case.4 (1) Handling, Storage, and Precautions: solutions are highly flammable; must be stored in the absence of proton sources, carbon acids, and oxygen. Flasks and Schlenk tubes should be flushed with dry Ar or N2. Handle with standard syringe technique to prevent contact of the solutions with oxygen and moisture. Solutions can be stored at 0 °C for months.