Synthesis of β-Lactams by Means of Sulfur-Controlled Regioselective Radical Cyclizations of N-Ethenyl-α-bromoalkanamides - Ishibashi, Hiroyuki; Kameoka, Chisato; Yoshikawa, Akiko; Ueda, Rika; Kodama, Kazuya; Sato, Tatsunori; Ikeda, Masazumi (Synlett, 1993)