Triphenylphosphine → 5-{4-[2(R)-t-butoxycarbonylaminopropoxy]benzyl}-3-triphenylmethylthiazolidine-2,4-dione

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Reaction Steps

13.2 g of diethyl azodicarboxylate were added dropwise to a solution of 20.7 g of triphenylphosphine in 300 ml of benzene, whilst ice-cooling. The mixture was then stirred at room temperature for 30 minutes, after which 35.0 g of 5-(4-hydroxybenzyl)-3-triphenylmethylthiazolidine-2,4-dione [prepared as described in Preparation 11] were added. The mixture was then stirred at room temperature for one hour, after which 13.2 g of (R)-2-t-butoxycarbonylamino-1-propanol were added to the mixture and the mixture was allowed to stand overnight at the same temperature. 40.9 g of triphenylphosphine, 23.68 ml of diethyl azodicarboxylate and 33 g of (R)-2-t-butoxycarbonylamino-1-propanol were then added, in turn and in 3 or 4 portions, to the mixture, and the mixture was stirred for 2 days. At the end of this time, the reaction mixture was freed from benzene by distillation under reduced pressure. The residue was then purified by column chromatography through silica gel, using a 1:3 by volume mixture of ethyl acetate and hexane as the eluent, to give 30.0 g of 5-{4-[2(R)-t-butoxycarbonylamino-1-propoxy]benzyl}-3-triphenylmethylthiazolidine-2,4-dione, melting at between 153° C. and 157° C.

Provenance & Evidence