Stereoselective S N 1 at non-classical carbocation Ilan Marek Technion - Israel Institute of Technology, Israel
Nucleophilic substitution at sp 3 carbon center is one of the most fundamental and common transformations in organic synthesis. While the stereochemical outcome for a S N 2 reaction proceeds with inversion of configuration, the unimolecular nucleophilic substitution S N 1 provides, in most cases, a racemic product in addition to potential elimination of a proton, as well as undesired hydride and alkyl rearrangements. Therefore, the control of the stereochemical outcome for a S N 1-type reactions remains very complex. Here, we intend to develop a predictable and reliable approach that would control the stereochemistry for a S N 1-type transformation, opening new avenues in stereoselective synthesis in acyclic systems through the use of non-classical carbocations. We are proposing a strategy that would produce either inversion or retention of configuration for a given S N 1 reaction for the preparation of regio-, diastereo- and enantiomerically enriched acyclic products possessing several adjacent stereocenters. Then, we will use the well-known skeletal rearrangements of carbocations as an approach of molecular editing to create a new stereo defined C–C bond at a position remote from the original carbocation, with a complete stereocontrol, even in the presence of sensitive functional groups. References 1. Stereoselective Construction of Tertiary Homoallyl Alcohols and Ethers by Nucleophilic Substitution at Quaternary Carbon Stereocenter Chen, K. Patel, I. Marek. Angew. Chem. Int. Ed. 2023 , 61 , e202212425 2. Stereospecific Nucleophilic Substitution at Quaternary Carbon Stereocenters Chen, K. Patel, I. Marek Chem 2023 , 9 , 266- 279 3. Stereoselective Synthesis of Polysubstituted Spiropentanes Y. Cohen, D. Toledano, I. Marek. J. Am. Chem. Soc. 2022 , 144 , 16732-16736 4. Borylated Cyclopropanes as Spring-Loaded Entities: Access to Vicinal Tertiary and Quaternary Stereocenters in Acyclic Systems. A. U. Augustin, S. Di Silvio, I. Marek J. Am. Chem. Soc. 2022 , 144, 16298-16302 5. Preparation of Distant Quaternary Carbon Stereocenters by Double Selective Ring-Opening of 1,1-Biscyclopropyl Methanol Derivatives Y. Siddaraju, J. Sabbatani, A. Cohen, I. Marek Angew. Chem. Int. Ed. 2022 , 61 , e202203652 6. Stereospecific Construction of Quaternary Carbon Stereocenters from Quaternary Carbon Stereocenters K. Patel, V. Lanke, I. Marek. J. Am. Chem. Soc. 2022 , 144 , 7066−7071
I14
© The Author(s), 2023
Made with FlippingBook Learn more on our blog