Pivaloyl chloride → HCID 91192837, Verbindung

Beteiligte Stoffe

Reaktionsschritte

Intermediate 34 (0.083 mg, 0.15 mmol) was dissolved in DCM/THF (9:1, 3 ml) using sonication by ultrasound. N,N-diisopropylethylamine (0.057 ml, 3.32 mmol) and trimethylacetyl chloride (0.021 ml, 0.16 mmol) were added at 0° C. with stirring under nitrogen. The reaction was allowed to warm to room temperature over 2 h, cooled again to 0° C. and N-hydroxy-propionamidine (0.015 g, 0.18 mmol in 0.5 ml tetrahydrofuran) added with stirring. The reaction was allowed to warm to room temperature and stirred for 16 h. The solvents were evaporated in vacuo and the reaction mixture dissolved in toluene (10 ml). The reaction was heated to reflux (120° C.) for 8 h. The product was purified on a Varian Mega Bond Elut cartridge (5 g Si, 20 ml size) eluting with ethyl acetate/methanol (50:1-1:1) to afford crude product as a yellow oil (0.01 g). The product dissolved in trifluoroacetic acid/water (4 ml, 9:1) at 0° C. with stirring under nitrogen for 4 h. The solvents were evaporated in vacuo, azeotroped with toluene (2×50 ml) and purification using Autoprep. HPLC afforded title compound as yellow gum (0.004 g) LCMS SYSTEM C Rt=2.39 min m/z=561 MH+

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