A stereodivergent and highly diastereoselective (dr up to >19:1 for both isomers), step economic (5-6 steps), and scalable synthesis (up to 14 g) of cis- and trans-2-substituted 3-piperidinols, the core motif of numerous bioactive compounds, providing efficient access to the NK-1 inhibitor L-733,060 is presented. Additionally, a "traceless" (referring to the simplified byproduct separation) cyclodehydration realizing simple P(OEt)3 as a substitute for PPh3 is developed.
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http://dx.doi.org/10.1021/ol4026588 | DOI Listing |
Chemistry
December 2024
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032, China.
A synergistic Pd/Cu catalyst system has been developed for stereodivergent transformation of Morita-Baylis-Hillman (MBH) carbonates and Schiff bases derived from simple amino acids to afford a series of optically active β-branched γ-methyleneglutamic acid derivatives with adjacent tertiary/tertiary and quaternary/tertiary stereocenters in high yields (up to 96 %) with excellent diastereo- and enantioselectivities (>20/1 dr and >99 % ee in most cases) under mild conditions. The use of SKP ligand is disclosed to be crucial for the success of the transformation, and in particular allowing the reaction to proceed at low catalyst loading (0.02 mol % for Pd and 0.
View Article and Find Full Text PDFJ Org Chem
December 2024
College of Chemical & Pharmaceutical Engineering, Hebei Province Key Laboratory of Molecular Chemistry for Drug, Hebei University of Science & Technology, Shijiazhuang 050018, China.
We report herein that three facile rearrangements of epoxy ketones can be employed for the efficient and practical synthesis of cephalotaxine, the parent member of the family of alkaloids. The Meinwald rearrangement of epoxy ketone (90%) was used for the preparation of the dense functional groups in the cyclopentane ring of cephalotaxine. A novel acid-catalyzed umpolung S2' rearrangement and the Wharton transposition reaction of epoxy ketones were also developed to synthesize the Mori intermediate via the key azaspiro allylic alcohols in a stereodivergent manner.
View Article and Find Full Text PDFOrg Lett
December 2024
Laboratory of Organic Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece.
Nature synthesizes epimeric C1 guaianolide congeners, key components of major natural product classes, through a single structurally flexible macrocyclic germacranolide core. Our rationally designed elemanolide-type scaffold () now mimics this natural process, enabling the stereodivergent synthesis of both C1 epimers of 6,12-guaianolide lactone motifs. An oxy-Cope/ene cascade acts as the key step of this process, generating two distinct conformers of an intermediate germacranolide, each leading to a specific C1 epimer.
View Article and Find Full Text PDFJ Am Chem Soc
November 2024
Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States.
Biocatalysis can be powerful in organic synthesis but is often limited by enzymes' substrate scope and selectivity. Developing a biocatalytic step involves identifying an initial enzyme for the target reaction followed by optimization through rational design, directed evolution, or both. These steps are time consuming, resource-intensive, and require expertise beyond typical organic chemistry.
View Article and Find Full Text PDFNat Commun
October 2024
Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, Jiangsu, P. R. China.
Carboxylesterases serve as potent biocatalysts in the enantioselective synthesis of chiral carboxylic acids and esters. However, naturally occurring carboxylesterases exhibit limited enantioselectivity, particularly toward ethyl 3-cyclohexene-1-carboxylate (CHCE, S1), due to its nearly symmetric structure. While machine learning effectively expedites directed evolution, the lack of models for predicting the enantioselectivity for carboxylesterases has hindered progress, primarily due to challenges in obtaining high-quality training datasets.
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