Scope and limitations in the use of N-(PhF)serine-derived cyclic sulfamidates for amino acid synthesis

Ring-opening of N-(PhF)serine-derived cyclic sulfamidate 17 was achieved with different nucleophiles (β-keto esters, β-keto ketones, dimethyl malonate, nitroethane, sodium azide, imidazole, and potassium thiocyanate) to prepare a variety of amino acid analogs. Two different pathways for ring opening of 17 were elucidated: direct nucleophilic displacement, as well as β-elimination followed by Michael addition. Furthermore, β-keto ester and β-keto ketone products 18k,18m, and 18i were converted to prolines and pyrazole amino acids.