How is (2S,5R,6R)-3,3-Dimethyl-7-oxo-6-[(phenylacetyl)amino]-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid (CAS: 61-33-6) typically synthesized?

(2S,5R,6R)-3,3-Dimethyl-7-oxo-6-[(phenylacetyl)amino]-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid can be synthesized through the condensation of (phenylacetyl)amine with 6,7-dimethyl-3-oxa-1-azabicyclo[3.2.0]heptane-2-carboxylic acid. The reaction is typically catalyzed by a strong base like sodium hydride to promote the nucleophilic attack, yielding a high isolated yield of about 85%. The process requires careful handling and is usually performed under an inert atmosphere to prevent decomposition.