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Synlett 1995; 1995(6): 615-616
DOI: 10.1055/s-1995-5032
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An Improved Asymmetric Synthesis of Piperazic Acids: Retro-Reaction in the Chiral Oxazolidinone Controlled Di-Azo Addition Reaction in a Dipolar Aprotic Medium

Carl P. Decicco* , Todd Leathers
  • *Chemical and Physical Sciences, The DuPont Merck Pharmaceutical Company, Experimental Station, Wilmington, Delaware, USA 19880-0353
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Publication Date:
31 December 2000 (online)

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The asymmetric addition intramolecular cyclization reaction to produce the piperazic acid precursor 3 was studied. A retroaddition of S -4-(phenylmethyl)oxazolidinyl-5-bromovalerimide to diazo-di-tert-butyl dicarboxylate in DMPU/THF was discovered. A process improvement based on the addition of catalytic tetra-butylammonium iodide to give 3 in 91% yield is reported.