Nitrogen → 1,1-Dimethylethyl 4-{[3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]methyl}-1-piperidinecarboxylate

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Reaction Steps

1,1-Dimethylethyl 4-{[3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]methylidene}-1-piperidinecarboxylate (92.48 g, 232 mmol) was dissolved in ethanol (1500 mL) and added to N2-purged 10% palladium on carbon (9 g, 4.25 mmol) in a 5 L hydrogenation flask. The resulting mixture was then deoxygenated by alternating N2 and vacuum supplies to the vessel. The flask was then placed under a hydrogen atmosphere with stirring. After 1 h the reaction had absorbed the theoretical volume of hydrogen and the hydrogen in the vessel was replaced by nitrogen by alternating the vacuum and nitrogen supplies. The mixture was then filtered through celite and the pad was washed well with ethanol. The filtrate was then concentrated to yield a straw coloured gum 87.6 g (94%). HPLC 3.11 min (ret time) (87.76% boronate) and 2.33 min (ret time) (6.66% boronic acid-boronate hydrolyses partially under HPLC conditions); LC-MS m/z 346 (M+H)+, 1.58 min (ret time) [product minus tBu group].

Provenance & Evidence