Yield:54333-75-4 100%

Reaction Conditions:

Stage #1: N,N-diethylpropanamidewith n-butyllithium;diisopropylamine in tetrahydrofuran;hexane at -78; for 0.5 h;Inert atmosphere;
Stage #2: with methyl chlorosulfate in tetrahydrofuran;hexane at -78; for 0.5 h;Inert atmosphere;

Steps:

α-chlorination of ketones

General procedure: To a solution of diisopropylamine (170 μL, 1.2 eq.) in dry THF (2 mL) in a flame dried round bottom flask under argon at 0 °C was added n-butyllithium (690 μL, 1.6 M in hexanes, 1.1 eq.), and the reaction mixture was stirred at this temperature for 15 minutes. It was then cooled to -78 °C and a solution of ketone (1) (1 mmol) in THF (2 mL) slowly added. Stirring at -78 °C was continued for a further 30 minutes and methyl chlorosulfate (100 μL, 1.1 eq.) was then added. After stirring at -78 °C for 30 minutes, the reaction was quenched with an aqueous saturated ammonium chloride solution (5 mL). The mixture was then extracted with dichloromethane (3 x 5 mL), the combined organic phases were dried with anhydrous magnesium sulfate and the solvent evaporated under vacuum affording the desired α-chloroketone 2.

References:

Silva, Saúl;Maycock, Christopher D. [Tetrahedron Letters,2018,vol. 59,# 13,p. 1233 - 1238] Location in patent:supporting information