Conformationally Restricted Nonchiral Pipecolic Acid Analogues

摘要

Practical syntheses of 2-azabicyclo[3.1.1]heptane- 1 -carboxylic (2,4-methanopipecolic), 2-azabicyclo[2.2.2]octane-1-carboxylic (2,5-ethanopipecolic), and 9-azabicyclo[3.3.1]nonane- 1 -carboxylic (2,6-propanopipecolic) acids are reported. The synthetic schemes are short (five, seven, and five steps,respectively) and result in reasonably high yields of the title compounds. The key step in the synthesesis the tandem Strecker reaction and intramolecular nucleophilic cyclization of ketones possessing aleaving group at the 6-position.