Direct N-acetyl enamine formation: lithium bromide mediated addition of methyllithium to nitriles

An improved protocol for N-acetyl enamine formation is disclosed which involves LiBr-mediated addition of MeLi to substituted nitriles. The resulting enamides are isolated in high yields and excellent purity which permits subsequent hydrogenation at very low catalyst loading.     

The Oxidation of Aldehydes to Methyl Esters using Trichloroisocyanuric Acid

Aldehydes are readily oxidized to methyl esters by a solution of methanol, pyridine, and trichloroisocyanuric acid in acetonitrile, acetone, or methylene chloride.     

Synthesis of aurachin D and isoprenoid analogues from the myxobacterium Stigmatella aurantiaca

Aurachins, a family of isoprenoid quinoline alkaloids isolated from the myxobacterium Stigmatella aurantiaca, possess multiple interesting bioactivities and were subject of intensive studies of biosynthesis. In this Letter, we describe the efficient few step total synthesis of the parent compound aurachin D and two isoprenoid analogues via Conrad–Limpach cyclization. The main antimicrobial and cytotoxic profiles of these derivatives were explored.     

Synthesis of rapamycin glycoconjugates via a CuAAC-based approach

The conversion of the C40 secondary hydroxyl group of rapamycin into the azido group was followed by copper catalyzed cycloaddition of the resulting azido-rapamcin with various unprotected propargyl O- and S-glycosides and a C-ethynyl derivative. This approach furnished a collection of triazole-bridged rapamycin glycoconjugates (14 examples) in 44–83% isolated yield.     

Harnessing Bottom‐Up Self‐Assembly To Position Five Distinct Components in an Ordered Porous Framework

Positioning a diverse set of building blocks in a well‐defined array enables cooperativity amongst them and the systematic programming of functional properties. The extension of this concept to porous metal–organic frameworks (MOFs) is challenging since the installation of multiple components in a well‐ordered framework requires careful design of the lattice topology, judicious selection of building blocks, and precise control of the crystallization parameters. Herein, we report how we met these challenges to prepare the first quinary MOF structure, FDM‐8, by bottom‐up self‐assembly from two metals, Zn^II and Cu^I, and three distinct carboxylate‐ and pyrazolate‐based linkers. With a surface area of 3643 m² g^?1, FDM‐8 contains hierarchical pores and shows outstanding methane‐storage capacity at high pressure. Furthermore, functional groups introduced on the linkers became compartmentalized in predetermined arrays in the pores of the FDM‐8 framework.     

Lipschitz Bounds and Nonuniform Ellipticity

We consider nonuniformly elliptic variational problems and give optimal conditions guaranteeing the local Lipschitz regularity of solutions in terms of the regularity of the given data. The analysis catches the main model cases in the literature. Integrals with fast, exponential-type growth conditions as well as integrals with unbalanced polynomial growth conditions are covered. Our criteria involve natural limiting function spaces and reproduce, in this very general context, the classical and optimal ones known in the linear case for the Poisson equation. Moreover, we provide new and natural growth a priori estimates whose validity was an open problem. Finally, we find new results also in the classical uniformly elliptic case. Beyond the specific results, the paper proposes a new approach to nonuniform ellipticity that, in a sense, allows us to reduce nonuniform elliptic problems to uniformly elliptic ones via potential theoretic arguments that are for the first time applied in this setting. © 2019 the Authors. Communications on Pure and Applied Mathematics is published by the Courant Institute of Mathematical Sciences and Wiley Periodicals, Inc.