Hydrochloric Acid → 1-(4,4,6-Trimethyl-[1,3]oxazinan-2-yl)-cyclopropanecarboxylic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

NaBH4 (3.18 g, 13.3 mmol) was dissolved in H2O (10 mL) and a drop of 10 M NaOH was added. To a solution of 1-(4,4,6-trimethyl-5,6-dihydro-4H-[1,3]oxazin-2-yl)-cyclopropanecarboxylic acid ethyl ester (10 g, 0.04 mol) in THF (33 mL) and ethanol (33 mL) was added the above alkaline solution of NaBH4 dropwise at −40° C. followed by 12M HCl (about 0.1 mL, the pH of the reaction mixture was adjusted to 6˜8). The resulting mixture was stirred at −40° C. for 1.5 hour. The reaction mixture was poured into water (100 mL) and basified with 10M NaOH to pH=10. The mixture was extracted with EtOAc (3×100 mL). The combined organic extracts were washed with brine, dried over Na2SO4 and concentrated to give crude 1-(4,4,6-trimethyl-[1,3]oxazinan-2-yl)-cyclopropanecarboxylic acid ethyl ester (9.0 g), which was used in the next step without purification.

Provenance & Evidence