The transition-metal-catalyzed amination of aryl halides has been the most powerful method for the formation of aryl amines over the past decades. Phenols are regarded as ideal alternatives to aryl halides as coupling partners in cross-couplings. An efficient palladium-catalyzed formal cross-coupling of phenols with various amines and anilines has now been developed. A variety of substituted phenols were compatible with the standard reaction conditions. Secondary and tertiary aryl amines could thus be synthesized in moderate to excellent yields.

A bioactive macrophage factor, the polypeptide daintain͞allograft inf lammatory factor 1 (AIF1), has been isolated from porcine intestine. It was discovered when searching for intestinal peptides with effects on insulin release, and its purification was monitored by the inf luence of the peptide fractions on pancreatic glucose-induced insulin secretion. Daintain͞AIF1 is a 146-aa residue polypeptide with a mass of 16,603 Da and an acetylated N terminus. An internal 44-residue segment with the sequence pattern -KR-KK-GKR-has a motif typical of peptide hormone precursors, i.e., dibasic sites for potential activation cleavages and at the sequentially last such site, the structure GKR. The latter is a signal for C-terminal amide formation in the processing of peptide hormones. Daintain͞AIF1 is immunohistochemically localized to microglial cells in the central nervous system and to dendritic cells and macrophages in several organs. A particularly dense accumulation of daintain͞AIF1-immunoreactive macrophages was observed in the insulitis affecting the pancreatic islets of prediabetic BB rats. When injected intravenously in mice, daintain͞AIF1 at 75 pmol͞kg inhibited glucose (1 g͞kg)-stimulated insulin secretion, with a concomitant impairment of the glucose elimination, whereas at higher doses (7.5 and 75 nmol͞kg), daintain͞AIF1 potentiated glucose-stimulated insulin secretion and enhanced the glucose elimination. Its dual inf luence on insulin secretion in vivo at different peptide concentrations, and the abundance of macrophages expressing daintain͞AIF1 in the pancreatic islets of prediabetic rats, suggest that daintain͞AIF1 may have a role in connection with the pathogenesis of insulin-dependent diabetes mellitus.

Aryl halides are very useful electrophiles for synthesizing various substituted aromatic compounds via metal-catalyzed cross-coupling reactions. Because of the high cost associated with their synthesis and the stoichiometric halide waste produced when using aryl halide feedstocks, cheaper and more sustainable alternatives have been explored, such as phenols. However, phenols have a very reactive hydroxyl group and a C–O bond with high dissociation energy. To overcome such challenges, earlier studies focused on finding ways to reduce the energy of the C–O bond while removing the active proton by transforming phenols into phenol derivatives (e.g., sulfonates, esters, carbamates, ethers, and metal salts). A greater ambition is to directly cross-couple phenols with nucleophiles via C–O cleavage. In this Perspective, we briefly summarize efforts and accomplishments concerning the cross-coupling of phenol derivatives and phenols.

The polypeptide DBI (diazepam-binding inhibitor) has been purified from the porcine upper intestine, where it is abundant. Porcine mature DBI is composed of 86 amino acid residues and has a blocked N-terminus. The primary structure, the first DBI structure determined at the protein level, differs from those indirectly deduced for human and rat DBI at 11 and 17 positions, respectively. In total, the three mammalian DBIs differ at 22 positions but have exactly identical C-terminal 1 1-residue segments, highly charged and ending with C-terminal isoleucine. The porcine DBI inhibits both the early and the late phase of glucose-induced insulin release from the isolated perfused rat pancreas. Thus, the results identify by direct analysis the presence of DBI at a non-cerebral localization (gut), establish a novel structural form (porcine) and demonstrate a novel bioactivity (on insulin release). These aspects are of special interest in relation to the conserved segments, including the one at the Cterminal end, which may constitute functionally important parts of the polypeptide. It is possible that DBI belongs to a new family of gut polypeptides which inhibit glucose-mediated insulin release by hormonal and/or neurocrine mechanisms.The polypeptide diazepam-binding inhibitor (DBI) was originally isolated from rat brain [l] and parts of its amino acid sequence were determined [I, 21. DBI is identical to or functionally related to the endogenous effector of the benzodiazepine recognition site, and it has therefore been given great attention in the neuropeptide research field. Cloning and expression of cDNA for human and rat DBI have been reported [3, 41, revealing different forms of DBI. None of the DBI forms has been completely analyzed directly at the peptide level.We have now isolated a polypeptide analogous to DBI from porcine intestine and have determined the amino acid sequence by peptide analyses. Furthermore, we have demonstrated that the porcine DBI decreased both the early and the late phases of glucose-induced insulin release from the isolated perfused rat pancreas.The primary structure and biological functions of DBI are greatly different from those of other known gastrointestinal polypeptides. DBI therefore represents a first member of a new polypeptide family which is broadly distributed in brain, gut and other tissues [3, 51. The present study demonstrates that it is found in high concentration in gut. MATERIALS AND METHODS Concentrate of thermostable intestinat po1ypeptide.sA concentrate was prepared essentially as described in detail [6]. Briefly, pieces of pig upper intestine were immersed for a few minutes into boiling water and then frozen. The material was minced while frozen and extracted with 0.5 M acetic acid at 0 -10°C. After filtration, the extracted peptides were adsorbed to alginic acid and eluted with 0.2 M HC1. In a modification of the earlier procedure, the pH of the eluate was brought to 3.5 k 0.1 before precipitation of the peptides by saturation with NaC1. The concentrate of thermostable...

A highly efficient Pd-catalyzed direct coupling of phenolic lignin model monomers and analogues with anilines to give cyclohexylamines using sodium formate as hydrogen donor is described.

No abstract

Symmetrical 1,3-diyne compounds can be easily synthesized via a transition-metal-free homocoupling reaction of 1-haloalkynes without base and oxidant. The method shows excellent functional group compatibility and high yields.

No abstract