Seven-, eight-, and nine-membered cyclic β-amino acids, precursors of platelet aggregation inhibitors, were synthesized for the first time starting from N-alkenyl amines and ethyl acrylate via ring-closing metathesis (RCM) as the key reaction. Synthesis of the corresponding enantiomerically pure β-amino acids was also accomplished in a similar manner using Evans’ asymmetric allylation.

Diverticular bleeding accounts for approximately 26%-40% of the cases of lower gastrointestinal bleeding. Rupture of the vasa recta at the neck or dome of the diverticula can he the cause of this bleeding. Colonoscopy aids in not only the diagnosis but also the treatment of diverticular bleeding after a steady bowel preparation. Endoscopic hemostasis involves several methods, such as injection/thermal contact therapy, clipping, endoscopic band ligation (ERL), hemostatic powder, and over-the-scope clips. Each endoscopic method can provide a secure initial hemostasis. With regard to the clinical outcomes after an endoscopic treatment, the methods reportedly have no significant differences in the initial hemostasis and early recurring bleeding, however, EBI, might prevent the need for transcatheter arterial embolization or surgery. In contrast, the long-term outcomes of the endoscopic treatments, such as a late bleeding and recurrent bleeding at 1 and 2 years, are not well known for diverticular bleeding. With regard to a cure for diverticular bleeding, there should be an improvement in both the endoscopic methods and the multilateral perspectives, such as diet, medicines, interventional approaches, and surgery.