Carbon Disulfide → Lithium Hexamethyldisilazide

HRID 653173Notes

Reaction equation

HRID 653173 reaction equation
C([Li:5])CCC.[CH3:6][Si:7]([CH3:14])([CH3:13])[NH:8][Si:9]([CH3:12])([CH3:11])[CH3:10].C(=S)=S.C(OC(=O)C)(=O)C>CCCCCC.O1CCCC1.O.ClCCl>[CH3:6][Si:7]([CH3:14])([CH3:13])[N-:8][Si:9]([CH3:12])([CH3:11])[CH3:10].[Li+:5]

Participants

9

Reactant 4

HCID 6348Carbon DisulfideHCID 7918Acetic AnhydrideHCID 13838HexamethyldisilazaneHCID 178418339Butyllithium

Product 1

HCID 2733832Lithium Hexamethyldisilazide

Reagents, catalysts & solvents 4

HCID 962WaterSolventHCID 6344DichloromethaneSolventHCID 8028TetrahydrofuranSolvent2×HCID 8058HexaneSolvent

Conditions

Temperature
-78 °C

Procedure

A solution of lithium hexamethyldisilazide was prepared by the addition of n-butyllithium in hexane (2.79 ml of a 1.6M solution) to 0.982 ml of hexamethyldisilazane in 8 ml of dry tetrahydrofuran at -10° C., while stirring under argon. The solution was cooled to -78° C. and added by cannula to a solution of 0.98 g of 4-nitrobenzyl 2-(4(R)-allylthio-3(S)-[1'(R)-{dimethyl-{2-methylprop-2-yl}silyloxy}ethyl]azetidin-2-on-1-yl) acetate in 8 ml of dry tetrahydrofuran at -78° C., with stirring under argon. After 5 minutes, 0.357 ml of carbon disulphide was added by syringe, followed by 0.748 ml of acetic anhydride. The mixture was allowed to warm to room temperature, and 30 ml of dichloromethane was added, followed by 30 ml of water. The organic layer was separated, and the aqueous layer was extracted with further dichloromethane. The combined organic extracts were washed with 1M HCl, with water, and with a 12% sodium chloride solution, and were then dried over magnesium sulphate and evaporated to give 1.38 g of an orange oil. 1.21 g of this crude product was chromatographed on silica gel using ethyl acetate/hexane mixtures as eluent to give 0.800 g of the title compound in purified form.

Workup

  1. stirringwith stirring under argon
  2. temperatureto warm to room temperature
  3. customThe organic layer was separated
  4. extractionthe aqueous layer was extracted with further dichloromethane
  5. washThe combined organic extracts were washed with 1M HCl, with water
  6. dry with materialwith a 12% sodium chloride solution, and were then dried over magnesium sulphate
  7. customevaporated

Sources & evidence

ORD record
ord-0b23d7580b3c4bfdbd5a8c4df04e4dcb
Source dataset
uspto-grants-1987_06
Patent number
US04675396

Reaction notes

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