A regioselective protocol for the synthesis of cyclopropyl derivatives that relies on Brookhart acid-catalyzed dehydrative coupling over substituted cyclopropylcarbinols without rearrangement is reported herein. The reactions proceed promptly at 25 °C with only 2.0 mol % catalyst loading and produce the cyclopropyl derivatives in excellent yields. This method is well tolerated with a vast range of cyclopropylcarbinols including aliphatic cyclopropylcarbinols, where no elimination product was obtained, demonstrating the protocol's utility. Further, the Hammett correlation suggested the formation of a cyclopropylcarbinyl cation followed by a coupling reaction. An extremely effective gram-scale reaction has also been demonstrated with a high turnover number.
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http://dx.doi.org/10.1021/acs.joc.2c00690 | DOI Listing |
Angew Chem Int Ed Engl
December 2024
Shenzhen Grubbs Institute and Department of Chemistry, Southern University of Science and Technology, Shenzhen, 518055, China.
Spiro skeletons have emerged as a privileged class of chiral carriers across various research fields, including asymmetric catalysis and functional materials, due to their remarkable configurational rigidity. However, limited structural diversity of spiro frameworks significantly restricts the expansion of their applications. Here we present a new class of axially chiral spiro-bisindole frameworks and report their first enantioselective construction via a chiral phosphoric acid-catalyzed intramolecular dehydrative cyclization reaction.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
December 2024
Department of Chemistry, Stanford University, Stanford, CA 94305.
The key first step in the oligomerization of monomers is to find an initiator, which is usually done by thermolysis or photolysis. We present a markedly different approach that initiates acid-catalyzed polymerization at the surface of water films or water droplets, which is the reactive phase during a wet-dry cycle in freshwater hot springs associated with subaerial volcanic landmasses. We apply this method to the oligomerization of different nucleic acids, a topic relevant to how it might be possible to go from simple nucleic acid monomers to long-chain polymers, a key step in forming the building blocks of life.
View Article and Find Full Text PDFPhys Chem Chem Phys
November 2024
Department of Chemistry, Indian Institute of Technology Madras, Chennai, 600036, India.
5-Hydroxymethylfurfural (HMF) is known for its potential in biofuel production and as a platform chemical for many commercially important molecules. The cost-effective large-scale production of HMF from glucose is hampered by its poor yield in aqueous media due to the formation of polymeric side products known as humins. Thus, reducing humins formation is a strategy for the efficient conversion of glucose to HMF.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
October 2024
Institut de Science et d'Ingénierie Supramoléculaires (ISIS) CNRS UMR 7006, Université de Strasbourg, 8 Allée Gaspard Monge, 67000, Strasbourg, France.
The catalytic deoxyamination of readily available 2-arylethanols offers an appealing, simple, and straightforward means of accessing β-(hetero)arylethylamines of biological interest. Yet, it currently represents a great challenge to synthetic chemistry. In most cases, the alcohol has to be either pre-activated in situ or converted into a reactive carbonyl intermediate, limiting the substrate scope for some methods.
View Article and Find Full Text PDFJ Biotechnol
November 2024
Department of Biological Engineering, College of Engineering, Konkuk University, Seoul, Republic of Korea; Institute for Ubiquitous Information Technology and Application, Konkuk University, Seoul, Republic of Korea. Electronic address:
Levulinic acid(LA) is produced through acid-catalyzed hydrolysis and dehydration of lignocellulosic biomass. It is a key platform chemical used as an intermediate in various industries including biofuels, cosmetics, pharmaceuticals, and polymers. Traditional LA production uses chemical conversion, which requires high temperatures and pressures, strong acids, and produces undesirable side reactions, repolymerization products, and waste problems Therefore, we designed an integrated process to produce LA from glucose through metabolic engineering of Pseudomonas putida KT2440.
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