Triethyl phosphite → (1S,5R,6S)-7-(diethoxy-phosphoryl)-5-methanesulfonyloxy-7-aza-bicyclo[4.1.0]hept-2-ene-3-carboxylic acid ethyl ester

Participants

Reaction Steps

(3R,4S,5R)-3-azido-4,5-bis-methanesulfonyloxy-cyclohex-1-enecarboxylic acid ethyl ester (44) was dissolved under argon with stirring in toluene. The clear solution was treated at room temperature with triethyl phosphite and stirred at room temperature for 30 minutes whereby after about 5 minutes gas evolution started. The light yellow reaction mixture was heated to reflux for 6 hours, evaporated at 40° C./60-10 mbar to yield of the crude product (1S,5R,6S)-7-(diethoxy-phosphoryl)-5-methanesulfonyloxy-7-aza-bicyclo[4.1.0]hept-2-ene-3-carboxylic acid ethyl ester (45) as a yellow oil, which was used in the next step without further purification. An analytical sample of (1S,5R,6S)-7-(diethoxy-phosphoryl)-5-methanesulfonyloxy-7-aza-bicyclo[4.1.0]hept-2-ene-3-carboxylic acid ethyl ester was obtained via a silica column chromatography using a 2:1 mixture of toluene and acetone. The combined fractions were evaporated and dried on a rotary evaporator at 40° C./250-10 mbar to obtain 45 as a yellow oil (45).

Provenance & Evidence