The subject invention provides methods and procedures for synthesis and/or semi-synthesis of the novel antibiotic arsinothricin (AST) and derivatives. Arsinothricin (AST), a new broad-spectrum organoarsenical antibiotic, is a non-proteinogenic analog of glutamate that effectively inhibits glutamine synthetase. The subject invention provides chemical synthesis of an intermediate in the pathway of AST synthesis, hydroxyarsinothricin (AST-OH), which can be converted to AST by enzymatic methylation catalyzed by the ArsM As(III) S-adenosylmethionine methyltransferase. The methods provide a source of the novel antibiotic that will be required for future clinical trials. The subject invention also provides AST derivatives as a new class of antibiotics.