1,5-Hydrogen atom transfer of α-iminyl radical cations: a new platform for relay annulation for pyridine derivatives and axially chiral heterobiaryls.

The exploitation of new reactive species and novel transformation modes for their synthetic applications have significantly promoted the development of synthetic organic methodology, drug discovery, and advanced functional materials. α-Iminyl radical cations, a class of distonic ions, exhibit great synthetic potential for the synthesis of valuable molecules. For their generation, radical conjugate addition to α,ß-unsaturated iminium ions represents a concise yet highly challenging route, because the in situ generated species are short-lived and highly reactive and they have a high tendency to cause radical elimination (ß-scission) to regenerate the more stable iminium ions. Herein, we report a new transformation mode of the α-iminyl radical cation, that is to say, 1,5-hydrogen atom transfer (1,5-HAT). Such a strategy can generate a species bearing multiple reactive sites, which serves as a platform to realize (asymmetric) relay annulations. The present iron/secondary amine synergistic catalysis causes a modular assembly of a broad spectrum of new structurally fused pyridines including axially chiral heterobiaryls, and exhibits good functional group tolerance. A series of mechanistic experiments support the α-iminyl radical cation-induced 1,5-HAT, and the formation of several radical species in the relay annulations. Various synthetic transformations of the reaction products demonstrate the usefulness of this relay annulation protocol for the synthesis of significant molecules.

Modular Assembly of 2-Aminoaniline Derivatives by Merging Hydroxylamine-Passerini and Hetero-Cope Rearrangement.

A metal-free three-component protocol that combines a hydroxylamine-Passerini reaction and hetero-Cope rearrangement was realized, which enables the modular assembly of a wide range of structurally new and interesting 2-aminoanilines bearing an α-hydroxyamide substructure.

Synthesis of a water-soluble naphthalene-based macrocycle and its host-guest properties.

Reported here is the synthesis of a naphthalene-based macrocycle bearing anionic carboxylato groups on the rims along with its complexation with cationic guests in aqueous media. The macrocycle could strongly bind guests in a molecular clip model with association constants of 106-107 M-1.

Urea Synthesis from Isocyanides and O-Benzoyl Hydroxylamines Catalyzed by a Copper Salt.

In the presence of CuOAc, a series of unsymmetric ureas can be generated in moderate to good yields under mild reaction conditions (10 mol% of CuOAc, 2 equiv t-BuONa or PhONa, 30 °C), using aryl isocyanides and O-benzoyl hydroxylamines as the readily accessible starting materials. The reactions might undergo a cascade process involving isocyanide insertion into the N-O bond and Mumm-type rearrangement. This work represents a rare example of isocyanide insertion into N-O bonds, which would extend isocyanide insertion chemistry.

Mechanical intestinal obstruction due to isolated diffuse venous malformations in the gastrointestinal tract: A case report and review of literature.

BACKGROUND: Isolated gastrointestinal venous malformations (GIVMs) are extremely rare congenital developmental abnormalities of the venous vasculature. Because of their asymptomatic nature, the diagnosis is often quite challenging. However, as symptomatic GIVMs have nonspecific clinical manifestations, misdiagnosis is very common. Here, we report a case of isolated diffuse GIVMs inducing mechanical intestinal obstruction. A literature review was also conducted to summarize clinical features, diagnostic points, treatment selections and differential diagnosis in order that doctors may have a comprehensive understanding of this disease. CASE SUMMARY: A 50-year-old man presented with recurrent painless gastrointestinal bleeding for two months and failure to pass flatus and defecate with nausea and vomiting for ten days. Digital rectal examination found bright red blood and soft nodular masses 3 cm above the anal verge. Computed tomography showed that part of the descending colon and rectosigmoid colon was thickened with phleboliths in the intestinal wall. Colonoscopy exhibited bluish and reddish multinodular submucosal masses and flat submucosal serpentine vessels. Endoscopic ultrasonography showed anechoic cystic spaces within intestinal wall. The lesions were initially thought to be isolated VMs involving part of the descending colon and rectosigmoid colon. Laparoscopic subtotal proctocolectomy, pull-through transection and coloanal anastomosis and ileostomy were performed. Histopathology revealed intact mucosa and dilated, thin-walled blood vessels in the submucosa, muscularis, and serosa involving the entire colorectum. The patient recovered with complete symptomatic relief during the 52-mo follow-up period. CONCLUSION: The diagnosis of isolated GIVMs is challenging. The information presented here is significant for the diagnosis and management of symptoms.