A series of -substituted cyclohexyldiaminophenolic ligands for the asymmetric Grignard synthesis of tertiary alcohols is reported. The 2,5-dimethylpyrrole-decorated ligand led to improved enantioselectivities and broadened the scope of the methodology. As an exemplar, we report an unprecedented highly selective one-step synthesis of gossonorol in 93% , also constituting the shortest formal syntheses of natural products boivinianin B and yingzhaosu C.
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http://dx.doi.org/10.1021/acs.orglett.0c02629 | DOI Listing |
Angew Chem Int Ed Engl
December 2024
Department of Chemistry, Faculty of Science, National University of Singapore, 3 Science Drive 2, Singapore, 117543, Singapore.
Asymmetric synthesis relies on seamless transmission of stereochemical information from a chiral reagent/catalyst to a prochiral substrate. The disruption by substrates' structural changes presents a hurdle in innovating generality-oriented asymmetric catalysis. Here, we report a strategy for substrate adaptability by exploiting a fundamental physicochemical phenomenon-ion hydration, in developing remote desymmetrization to access P-stereogenic triarylphosphine oxides and sulfides.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
November 2024
State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, 222 South Tianshui Road, Lanzhou, Gansu Province, 730000, China.
Kalmanol (1) is the first isolated kalmane-type grayanoid featuring a highly oxidized 5/8/5/5 tetracyclic carbon skeleton and 9 contiguous stereocenters. We have accomplished the efficient and asymmetric total synthesis of 1 in 16 steps from known compounds (20 steps from commercially available starting materials) by a modular synthetic strategy. A tetracyclic intermediate was prepared in a convergent manner through a Grignard reaction and a subsequent ring-closing metathesis reaction of two enantiomerically enriched fragments.
View Article and Find Full Text PDFOrg Biomol Chem
December 2024
Department of Biochemistry, UT Southwestern Medical Center, Dallas, Texas 75390, USA.
We describe the development of a unified synthetic strategy for the preparation of all known 5/5-spirocyclic spiroindimicin (SPM) alkaloids, namely spiroindimicins B-G. The present synthetic route relies on four fundamental transformations: Grignard-based fragment coupling between halogenated pyrrolemetal and isatin partners, Suzuki coupling to generate a triaryl scaffold encompassing all requisite skeletal atoms of the natural products, Lewis acid-mediated spirocyclization to construct the 5/5-spirocyclic core, and chemoselective lactam reduction. The developed syntheses are step-economic (6-7 steps from commercial materials), scalable, and amenable to analogue synthesis.
View Article and Find Full Text PDFACS Catal
September 2024
Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands.
Catalytic dearomatization of pyridinium salts is a powerful technique for constructing chiral -heterocycles, which are crucial in alkaloid natural products and drugs. Despite its potential, progress in metal-catalyzed asymmetric dearomatization of pyridinium derivatives has been limited. Here, we present the enantioselective 1,4-dearomatization of pyridinium salts using Grignard reagents and chiral copper catalysis.
View Article and Find Full Text PDFTetrahedron Lett
August 2024
Providence College, 1 Cunningham Square, Providence, Rhode Island, USA 02918.
The rational design of atropisomeric small molecules is becoming increasingly common in chemical synthesis as a result of the unique advantages this property provides in drug discovery, asymmetric catalysis, and chiroptical activity. In this study, we designed a synthesis of a configurationally stable β-carboline in six steps. Our synthesis made use of an innovative Grignard addition/elimination reaction that formed an yne-ynamide precursor that then reacted with ethyl cyanoformate in a rhodium(I)-catalyzed [2+2+2] cyclotrimerization reaction to give the atropisomeric β-carboline in excellent yield, good enantioselectivity, and excellent regioselectivity.
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