Development of perfluoroarene-arene interactions for macrocyclic en-yne metathesis and the total synthesis of macrocyclic natural products

Macrolactonization Reactions Driven by a Pentafluorobenzoyl Group*

Macrolactones constitute a privileged class of natural and synthetic products with a broad range of applications in the fine chemicals and pharmaceutical industry. Despite all the progress made towards their synthesis, notably from seco-acids, a macrolactonization promoter system that is effective, selective, flexible, readily available, and, insofar as possible, compatible with manifold functional groups is still lacking. Herein, we describe a strategy that relies on the formation of a mixed anhydride incorporating a pentafluorophenyl group which, due to its high electronic activation enables a convenient access to macrolactones, macrodiolides and esters with a broad versatility. Kinetic studies and DFT computations were performed to rationalize the reactivity of the pentafluorophenyl group in macrolactonization reactions.

Exploiting ortho-substitution effect on formation of oxygen-containing [10]paracyclophane through ring-closing metathesis

The synthesis of strained paracyclophanes is facilitated byortho-substitution effect on phenyl ring.

Twisting and piezochromism of phenylene-ethynylenes with aromatic interactions between side chains and main chains

This paper describes a series of three-ring phenylene-ethynylenes (PEs) in which specific, non-covalent arene–arene interactions control conformation in the solid-state.

Hirsutellones and beyond: figuring out the biological and synthetic logics toward chemical complexity in fungal PKS-NRPS compounds

Covering: up to early 2013. Fungal polyketides and their hybrid non ribosomal peptide derivatives are characterized by often striking structural features and biological activities. Their diversity and their complexity arise from highly organized and programmable biosynthetic pathways and have been challenged by many synthetic chemists. This review will conceptually illustrate how complexity can be generated, starting from a general biosynthetic purpose (the fundaments of PKS-NRPS assembly lines) and finally showing how the particular class of hirsutellone compounds has emerged from such processes in relation to post-elongation and secondary tailoring events. Synthetic efforts to produce these natural products will be described with a special emphasis on complexity-generating strategies and steps. Thus, the biosynthetic and synthetic works will be analyzed in a continuous flow, focusing on both the logic of Nature and organic chemists.

Macrocyclic drugs and synthetic methodologies toward macrocycles

Macrocyclic scaffolds are commonly found in bioactive natural products and pharmaceutical molecules. So far, a large number of macrocyclic natural products have been isolated and synthesized. The construction of macrocycles is generally considered as a crucial and challenging step in the synthesis of macrocyclic natural products. Over the last several decades, numerous efforts have been undertaken toward the synthesis of complex naturally occurring macrocycles and great progresses have been made to advance the field of total synthesis. The commonly used synthetic methodologies toward macrocyclization include macrolactonization, macrolactamization, transition metal-catalyzed cross coupling, ring-closing metathesis, and click reaction, among others. Selected recent examples of macrocyclic synthesis of natural products and druglike macrocycles with significant biological relevance are highlighted in each class. The primary goal of this review is to summarize currently used macrocyclic drugs, highlight the therapeutic potential of this underexplored drug class and outline the general synthetic methodologies for the synthesis of macrocycles.

Aromatic rings in chemical and biological recognition: energetics and structures

This review describes a multidimensional treatment of molecular recognition phenomena involving aromatic rings in chemical and biological systems. It summarizes new results reported since the appearance of an earlier review in 2003 in host-guest chemistry, biological affinity assays and biostructural analysis, data base mining in the Cambridge Structural Database (CSD) and the Protein Data Bank (PDB), and advanced computational studies. Topics addressed are arene-arene, perfluoroarene-arene, S⋅⋅⋅aromatic, cation-π, and anion-π interactions, as well as hydrogen bonding to π systems. The generated knowledge benefits, in particular, structure-based hit-to-lead development and lead optimization both in the pharmaceutical and in the crop protection industry. It equally facilitates the development of new advanced materials and supramolecular systems, and should inspire further utilization of interactions with aromatic rings to control the stereochemical outcome of synthetic transformations.

Control of the stability of a protein-RNA complex by the position of fluorine in a base analogue

The effects of modifying the electronic characteristics of nonpolar base analogues substituted at positions involved in stacking interactions between SL2 RNA and the U1A protein are described. A surprisingly large difference in the stability between complexes formed with base analogues that differ only in the position of substitution of a single fluorine atom is observed. The results of high-level ab initio calculations of the interactions between the nonpolar base analogue and the amino acid side chain correlate with the experimentally observed trends in complex stability, which suggests that changes in stacking interactions that result from varying the position and degree of fluorine substitution contribute to the effects of fluorine substitution on the stability of the U1A-SL2 RNA complex.

Construction of the cyclophane core of the hirsutellones via a RCM strategy

Construction of the highly strained [10]-paracyclophane core of the hirsutellones has been completed via an effective RCM strategy.

A relay ring-closing metathesis synthesis of dihydrooxasilines, precursors of (Z)-iodo olefins

A convenient Grubbs II metathesis provides dihydrooxasilines by relay RCM (RRCM). Dihydrooxasilines undergo ring opening to give Z-vinyl silanes. These can then be converted to Z-vinyl iodides. This sequence provides a short, high yield, and convenient route to trisubstituted Z-vinyl iodides, useful intermediates for the preparation of polypropionate antibiotics.

Exploiting quadrupolar interactions in the synthesis of the macrocyclic portion of longithorone C

2,3,4,5,6-Pentafluorobenzyl and 3,5-bistrifluoromethylbenzyl ester auxiliaries can enable difficult macrocyclizations to afford rigid all-carbon paracyclophanes. The effectiveness of these auxiliaries has been demonstrated in preparing the carbon skeleton of the macrocyclic natural product longithorone C.