Divalent Activation in Temporary Phosphate Tethers:  Highly Selective Cuprate Displacement Reactions

Whitehead, A.; McParland, James P.; Hanson, Paul R.

doi:10.1021/ol061756r

Cited by 29 publications

(5 citation statements)

References 13 publications

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“…These experiments indicate that the major pathway for ring opening and ring closing occurs by an S N 2/S N 2 process, while suggesting that an iodine or iodide-mediated interconversion between the enolates is likely operative under the reaction conditions. Although we note that these results do not completely rule out the possibility of a minor S N 2′ ring opening process, orbital arguments would prevent such a possibility since a coplanar alignment of the alkene π* and the σ* of the C-leaving group is required for S N 2′ processes to occur . However, in our system the π* of the alkene and the σ* of the C−C cyclopropane system are almost orthogonal, thereby disfavoring such a ring-opening process (Scheme ).…”

Section: Resultsmentioning

confidence: 66%

Synthesis of Highly Functionalized Pyrrolidines via a Selective Iodide-Mediated Ring Expansion of Methylenecyclopropyl Amides

Scott

Lautens

2008

J. Org. Chem.

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This manuscript describes a highly selective iodide-mediated, tandem Mannich/cyclization to afford trans-2,3-disubstituted pyrrolidines from methylenecyclopropyl amides in good to excellent yields and selectivities. The reaction scope has been drastically expanded to include a wide array of aromatic, heteroaromatic and alpha,beta-unsaturated imines, as well as a variety of methylenecyclopropyl amides. Additionally, mechanistic studies were carried out to ascertain the nature of the ring-opening/ring-closing mechanism using deuterated substrates. Results from these studies indicate that the primary mechanism is an S(N)2/S(N)2 ring opening/ring closing and that iodine- or iodide-mediated isomerization of the iodo enolate is likely occurring.

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Section: Resultsmentioning

confidence: 66%

Synthesis of Highly Functionalized Pyrrolidines via a Selective Iodide-Mediated Ring Expansion of Methylenecyclopropyl Amides

Scott

Lautens

2008

J. Org. Chem.

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“…Furthermore, other methods for the stereoselective assembly of long sequences of stereocenters in polypropionates have been developed. These methods include crotylations [ 10 , 11 , 12 ], allenylations [ 13 , 14 , 15 ], selective radical processes [ 16 , 17 , 18 , 19 ], sequential substitutions [ 20 , 21 ], epoxide ring openings [ 22 , 23 , 24 , 25 ], Diels–Alder [ 26 ], and others [ 27 , 28 , 29 , 30 ] ( Figure 3 ).…”

Section: Introductionmentioning

confidence: 99%

Epoxide-Based Synthetic Approaches toward Polypropionates and Related Bioactive Natural Products

Rodríguez-Berríos

Isbel

Bugarin

2023

IJMS

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Polypropionate units are a common structural feature of many of the natural products in polyketides, some of which have shown a broad range of antimicrobial and therapeutic potential. Polypropionates are composed of a carbon skeleton with alternating methyl and hydroxy groups with a specific configuration. Different approaches have been developed for the synthesis of polypropionates and herein we include, for the first time, all of the epoxide-based methodologies that have been reported over the years by several research groups such as Kishi, Katsuki, Marashall, Miyashita, Prieto, Sarabia, Jung, McDonald, etc. Several syntheses of polypropionate fragments and natural products that employed epoxides as key intermediates have been described and summarized in this review. These synthetic approaches involve enatio- and diastereoselective synthesis of epoxides (epoxy-alcohols, epoxy-amides, and epoxy-esters) and their regioselective cleavage with carbon and/or hydride nucleophiles. In addition, we included a description of the isolation and biological activities of the polypropionates and related natural products that have been synthetized using epoxide-based approaches. In conclusion, the epoxide-based methodologies are a non-aldol alternative approach for the construction of polypropionate.

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“…Following our initial investigations, we evaluated various transition metal and ligand combinations for their catalytic activity, regioselectivity, and stereoselectivity. We obtained ether 7 in 91% yield with 15:1 diastereoselectivity from alcohol 8 and ester 9a in the presence of Wilkinson’s catalyst (0.05 equiv), CuI (2.04 equiv), P(OCH3) 3 (0.4 equiv), LiHMDS (1.94 equiv), and 4 Å MS (1 g/mmol) in THF (Table , entry 1). Using bulky ester 9b generated only a trace amount of the desired product (entry 2).…”

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confidence: 99%

Synthesis of the Disaccharide Core of Ezomycin Nucleosides

Fan

Jiang

et al. 2023

Org. Lett.

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The ezomycins make up a class of complex nucleoside antibiotics that share a common disaccharide core. Herein we present an efficient synthesis of this core from diacetone-d-allose, using a ruthenium-catalyzed asymmetric allylic etherification and a de novo carbohydrate synthesis based on the diastereoselective Henry reaction. Our strategy overcomes several challenges, such as introducing a dense array of functional groups and creating consecutive stereocenters with high selectivity. This approach enables the rapid preparation of disaccharides and paves the way for the total synthesis of ezomycins.

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Divalent Activation in Temporary Phosphate Tethers: Highly Selective Cuprate Displacement Reactions

Cited by 29 publications

References 13 publications

Synthesis of Highly Functionalized Pyrrolidines via a Selective Iodide-Mediated Ring Expansion of Methylenecyclopropyl Amides

Synthesis of Highly Functionalized Pyrrolidines via a Selective Iodide-Mediated Ring Expansion of Methylenecyclopropyl Amides

Epoxide-Based Synthetic Approaches toward Polypropionates and Related Bioactive Natural Products

Synthesis of the Disaccharide Core of Ezomycin Nucleosides

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