An Efficient Procedure for Preparation of C‐ and N‐Protected 1‐Aminocyclobutane Carboxylic Acid

Abstract

An efficient method for the synthesis of differentially protected 1‐aminocyclobutane carboxylic acid is described. Synthetically useful intermediates 7 and 8 were prepared from ethyl 1‐bromocyclobutanecarboxylate in excellent yields (95% and 69%, respectively).

Keywords:

• 1‐Aminocyclobutane carboxylic acid
• Ethyl 1‐bromocyclobutane carboxylate
• Tertiary α‐bromo esters

Notes

^aAlthough methanol is the preferred solvent, some trans-esterification to the methyl ester can occur at this stage (∼5–10%). However, performing the hydrogenation in ethanol provides 7 free of methyl ester.