Piperonyl alcohol → 2(R)-[(3,4-methylenedioxybenzyl)-(4-methoxy-2,3,6-trimethylbenzene-sulfonyl)amino]-3(S)-(triethylsilyloxy)butyric acid 3,4-methylenedioxybenzyl ester

Participants

Reaction Steps

To a solution of 2(R)-(4-methoxy-2,3,6-trimethylbenzenesulfonyl-amino)-3(S)-(triethylsilyloxy)butyric acid 3,4-methylenedioxybenzyl ester (3.3 g, 5.7 mmol) in benzene (100 mL) at 0° C. was added 3,4-methylenedioxyphenyl methanol (1.3 g, 8.5 mmol), tri-n-butylphosphine (2.1 mL, 8.5 mmol), followed by 1,1′-[azodicarbonyl]dipiperidine (2.2 g, 8.5 mmol). The reaction mixture was allowed to warm to room temperature over 4 h. After 72 h, the reaction mixture was diluted with an equal volume of hexanes, cooled to 0° C. for 2 h and filtered. The residue was concentrated and chromatographed (300 g SiO2, 15% ethyl acetate-hexanes) to afford 2(R)-[(3,4-methylenedioxybenzyl)-(4-methoxy-2,3,6-trimethylbenzenesulfonyl)amino]-3(S)-(triethylsilyloxy)butyric acid 3,4-methylenedioxybenzyl ester (3.3 g) as a yellow oil.

Provenance & Evidence