cyclo(valylvalyl) → HCID 7075896, compound

Participants

Reaction Steps

Upon refluxing a dioxane solution containing 2 mmol of (2S,3S)-2-amino-3-methylpentan-1-ol and 0.02 mmol of catalyst 1 for 19 hrs and cooling the reaction mixture, the solid product precipitated and was filtered off and dried under vacuum to give pure 3-(sec-butyl)-6-(sec-butyl)piperazine-2,5-dione 7c in 72% yield (Table 9, entry 2). The structure was confirmed by NMR and MS spectroscopies. Under the same conditions, cyclic peptidation of (S)-2-amino-3-methylbutan-1-ol led to 3,6-diisopropylpiperazine-2,5-dione 7d as an insoluble solid which separated from the reaction mixture and was isolated by filtration and dried under vacuum to give 78% of (3S,6S)-3,6-diisopropylpiperazine-2,5-dione 7d (Table 9, entry 3). The optical rotation of the pure product (−52°) was essentially the same as reported in the literature (−) 54°. Thus, under these experimental condition, no racemization took place.

Provenance & Evidence