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Simple and efficient protocol for synthesis of N-Boc protected oxazolidines via cyclization of chiral serine

Saurabh Khadse, Prashant Chaudhari

In present work we wish to report synthesis and characterization of (S)- tert-butyl 4-formyl-2,2-dimethyloxazolidine-3-carboxylate (5) derivatives from L-Serine as a chiral starting material.Amino terminal of L-serine was protected by (Boc)2O (ditertiary butyl dicarbonate); Cyclization of C- and Nterminal protected á-L amino acid is achieved by refluxing itwith DMP (2, 2 dimethoxy propane) and PTSA (para toluene sulfonic acid) in benzene. Structure of the productwas confirmed by FT-IR,LC-MS, 1H NMR and13C NMR. Retention of stereochemistry was confirmed by optical rotation obtained on polarimeter. After hydrolysis of methyl ester of 2, 2- dimethyloxazolidine, alcohol as side chain obtained underwent for ‘Swern OxidationÂ’ using TFAA (Trifluoro acetic anhydride), TEA and DMSO to afford aldehyde.(S)-tert-butyl 4-formyl-2,2-dimethyloxazolidine-3-carboxylate as final product, which is important synthetic precursor for synthesis of medicinally significant candidates.