We report an asymmetric synthesis of (1R,4R)-N-acyl-2-oxa-5-aza-bicyclo[2.2.1]heptan-3-ones, starting from the inexpensive and commercially available trans-4-hydroxy-L-proline and achieved by treating N-acyl-trans-4-hydroxy-L-prolines with acetic anhydride. The formation of intermediate mesoionic compounds may explain the formation of N-acyl-2-oxa-5-aza-bicyclo[2.2.1]heptan-3-ones with (R)-absolute configuration at C(4). Acidic cleavage of these lactones readily affords N-acyl-cis-4-hydroxy-D-prolines or cis-4-hydroxy-D-proline in good yields.
Stereoselective synthesis of (1R,4R)-N-acyl-2-oxa-5-aza-bicyclo[2.2.1]heptan-3-ones via mesoionic compounds. An improved synthesis of cis-4-hydroxy-D-proline / P. Dalla Croce, C. La Rosa. - In: TETRAHEDRON-ASYMMETRY. - ISSN 0957-4166. - 13:2(2002), pp. 197-201. [10.1016/S0957-4166(02)00074-5]
Stereoselective synthesis of (1R,4R)-N-acyl-2-oxa-5-aza-bicyclo[2.2.1]heptan-3-ones via mesoionic compounds. An improved synthesis of cis-4-hydroxy-D-proline
P. Dalla CrocePrimo
;C. La RosaUltimo
2002
Abstract
We report an asymmetric synthesis of (1R,4R)-N-acyl-2-oxa-5-aza-bicyclo[2.2.1]heptan-3-ones, starting from the inexpensive and commercially available trans-4-hydroxy-L-proline and achieved by treating N-acyl-trans-4-hydroxy-L-prolines with acetic anhydride. The formation of intermediate mesoionic compounds may explain the formation of N-acyl-2-oxa-5-aza-bicyclo[2.2.1]heptan-3-ones with (R)-absolute configuration at C(4). Acidic cleavage of these lactones readily affords N-acyl-cis-4-hydroxy-D-prolines or cis-4-hydroxy-D-proline in good yields.
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