Boron trifluoride etherate → (3R,4S,5R)-4-(diethoxy-phosphorylamino)-3-(1-ethyl-propoxy)-5-methanesulfonyloxy-cyclohex-1-enecarboxylic acid ethyl ester

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Reaction Steps

To a solution of 1.94 g of 16 and 3-pentanol (20 mL) cooled to 0-5° C. in a 50 mL round-bottom flask equipped with a magnetic stirrer and an argon gas supply was added 736 μl boron trifluoride ethyl etherate. The reaction mixture was stirred for 16 h at RT and the reaction mixture was then diluted with 50 mL of EtOAc and twice extracted with 70 mL of water. The organic phase was separated, dried (Na2SO4, 25 g) filtered and concentrated in a rotary evaporator at 40° C./70-10 mbar to afford 2.18 g of the crude product as a yellow oil. The crude product was purified by SiO2 column chromatography eluting with tert-butyl methyl ether. The combined fractions were evaporated and dried on a rotary evaporator at 40° C./250-10 mbar to afford 1.47 g of 18 as a light yellow solid.

Provenance & Evidence