In many significant natural products, furans are a key motif. These oxygen-containing five-membered heterocycles are also versatile building blocks in the construction of highly complex target structures. As such, they are important scaffolds in organic and pharmaceutical chemistry.
As reported in the European Journal of Organic Chemistry, A. Stephen K. Hashmi and a team at Universität Heidelberg (Germany) have now introduced a general protocol for the preparation of highly substituted furans through a gold-catalyzed cyclization reaction.
The efficiency of reactions is often thought of in terms of atom economy, and the search for more efficient alternatives to classical chemical reactions is now an area of intense research. In this context, transition-metal catalysts are becoming a popular choice amongst chemists, because they are often used in only very small amounts, which conforms to the atom-economy rule and minimizes waste. Notably, in contrast to the often harsh conditions required to perform classical chemical transformations, most transition-metal catalyzed reactions can be performed under mild reaction conditions and within a short timeframe.
Because gold catalysts are robust, their popularity has increased significantly in the last few years. Gold catalysts can easily be handled in air, and they are also tolerant to water. Moreover, gold catalysts often show higher activity and higher selectivity than their more popular palladium counterparts. Gold is particularly well suited for substrates that bear a triple carbon–carbon bond (i.e., an alkyne), as it coordinates preferentially to this bond, resulting in a highly reactive complex that is prone to attack. As such, the gold-catalyzed cyclization of an alkyne tethered to an alcohol can provide easy access to highly substituted furans.
The German research team found that the gold(I)-catalyzed cyclization of various 2-alkynylallyl alcohols proceeded well and afforded the desired furan products with the use of low catalyst loadings under very mild reaction conditions. Importantly, both di- and trisubstituted furans could be obtained, which allows structural variety in the building blocks. Bifunctional substrates could also be cyclized to provide chemically interesting bisfurans. This synthetically simple route provides quick and easy access to highly substituted furan building blocks, which may help to facilitate the study of this important class of compounds.
Author: A. Stephen K. Hashmi, Universität Heidelberg (Germany),
Title: Cyclization of 2-Alkynylallyl Alcohols to Highly Substituted Furans by Gold(I)–Carbene Complexes
European Journal of Organic Chemistry, Permalink to the article: http://dx.doi.org/10.1002/ejoc.201001479
A. Stephen K. Hashmi | Wiley-VCH
During HIV infection, antibody can block B cells from fighting pathogens
14.08.2018 | NIH/National Institute of Allergy and Infectious Diseases
First study on physical properties of giant cancer cells may inform new treatments
14.08.2018 | Brown University
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur
What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...
The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.
Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...
08.08.2018 | Event News
27.07.2018 | Event News
25.07.2018 | Event News
14.08.2018 | Information Technology
14.08.2018 | Life Sciences
14.08.2018 | Life Sciences