The present invention relates to specific beta-lactone compounds and compositions thereof for the treatment of infections, such as, e. A method of preparing a 2-alkyl amino acid involves reacting cysteine and an aryl carboxylic acid to form a thiazoline ring, stereospecifically alkylating the thiazoline ring, and hydrolyzing the thiazoline ring to obtain a 2-alkylcysteine. The telepresence unit includes a directional microphone for capturing sounds at the remote location, and means for converting the captured sounds into a stream of data to be communicated to the user station. The derivative and salt have antidiabetic activity. A trench is formed in the semiconductor substrate and adjoining a second side of the active region. In one example, the surge protector has a first set value for responding to an applied battery voltage and a second set value for responding to a combination voltage that includes a battery voltage plus a ringing voltage.