Compounds having antibacterial activity are disclosed. The compounds have the following structure (I):
including stereoisomers, pharmaceutically acceptable salts and prodrugs thereof, wherein A, B, D, E, G, R
1
, R
2
, R
3
, R
4
, R
5
, R
6
and R
7
are as defined herein. Methods associated with preparation and use of such compounds, as well as pharmaceutical compositions comprising such compounds, are also disclosed.
Stereoselective synthesis of non-proteinogenic amino acids via Michael addition to 3,4-didehydropyroglutamate derivative in which the carboxyl function is protected as a 2,7,8-trioxabicyclo[3.2.1]octane (ABO ester) group is described. The obtained 3-substituted pyroglutamic ABO ester was directly converted to 3-substituted glutamic acids such as chlorpheg by acidic hydrolysis, whereas 3-substituted