Diastereoselective Palladium-Catalyzed Formate Reduction of Allylic Carbonates en Route to Polypropionate Systems

Chau, Anh; Paquin, Jean‐François; Lautens, Mark

doi:10.1021/jo052267s

Cited by 31 publications

(13 citation statements)

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“…5a ). In addition to its mechanistic significance, this experiment demonstrates a method to prepare chiral isotopically labelled stereogenic centres that complements allylic deuteration using formic acid- d 2 29 , 30 . Using 5c , 2ac was obtained, where the deuterium label was incorporated into the internal vinylic carbon (Fig.…”

Section: Resultsmentioning

confidence: 99%

Enantioselective semireduction of allenes

Chen

Dong

2017

Nat Commun

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Rh-hydride catalysis solves a synthetic challenge by affording the enantioselective reduction of allenes, thereby yielding access to motifs commonly used in medicinal chemistry. A designer Josiphos ligand promotes the generation of chiral benzylic isomers, when combined with a Hantzsch ester as the reductant. This semireduction proceeds chemoselectively in the presence of other functional groups, which are typically reduced using conventional hydrogenations. Isotopic labelling studies support a mechanism where the hydride is delivered to the branched position of a Rh-allyl intermediate.

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Section: Resultsmentioning

confidence: 99%

Enantioselective semireduction of allenes

Chen

Dong

2017

Nat Commun

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“…Synthesis of acid 10 : The synthesis of building block 10 (corresponding to retron I‐2 with PG=TBS; Schemes and ) departed from 2‐butynol ( 3 ), which was submitted to Corey’s reductive alumination/iodination22 procedure, followed by PMB‐protection of the free hydroxyl group by reaction with PMB‐trichloroacetimidate (Scheme ) 23. Conversion of the resulting Z vinyl iodide 4 into the corresponding vinyl lithium species with n BuLi followed by treatment with racemic epichlorohydrin and BF 3 ⋅OEt 2 then afforded chlorohydrin 5 in 50–70 % yield.…”

Section: Resultsmentioning

confidence: 99%

Total Synthesis of (−)‐Zampanolide and Structure–Activity Relationship Studies on (−)‐Dactylolide Derivatives

Zurwerra¹,

Glaus²,

Betschart³

et al. 2012

Chemistry A European J

116

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A new total synthesis of the marine macrolide (-)-zampanolide (1) and the structurally and stereochemically related non-natural levorotatory enantiomer of (+)-dactylolide (2), that is, ent-2, has been developed. The synthesis features a high-yielding, selective intramolecular Horner-Wadsworth-Emmons (HWE) reaction to close the 20-membered macrolactone ring of 1 and ent-2. The β-keto phosphonate/aldehyde precursor for the ring-closure reaction was obtained by esterification of a ω-diethylphosphono carboxylic acid fragment and a secondary alcohol fragment incorporating the THP ring that is embedded in the macrocyclic core structure of 1 and ent-2. THP ring formation was accomplished through a segment coupling Prins-type cyclization. Employing the same overall strategy, 13-desmethylene-ent-2 as well as the monocyclic desTHP derivatives of 1 and ent-2 were prepared. Synthetic 1 inhibited human cancer cell growth in vitro with nM IC(50) values, while ent-2, which lacks the diene-containing hemiaminal-linked side chain of 1, is 25- to 260-fold less active. 13-Desmethylene-ent-2 as well as the reduced versions of ent-2 and 13-desmethylene-ent-2 all showed similar cellular activity as ent-2 itself. The same activity level was attained by the monocyclic desTHP derivative of 1. Oxidation of the aldehyde functionality of ent-2 gave a carboxylic acid that was converted into the corresponding N-hexyl amide. The latter showed only μM antiproliferative activity, thus being several hundred-fold less potent than 1.

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“…Therefore, Teichert's allylic reduction strategy and our own are complementary to each other, and thus enrich the diversity of available reactions. Moreover, treatment of 15 and 16 with hydrogen in the presence of Pd/C in MeOH gave allylic reduction product 19 in 95 % yield; this represents an extension of the palladium‐catalyzed formate reduction of allylic carbonates . Subsequently, treatment of 19 with DDQ in a mixed solvent of acetone and H 2 O (10:1, v/v) at room temperature gave undesired product 18 in 70 % yield, along with 10 % of recovered 19 , but none of the desired drimanal p ‐benzoquinone 20 was obtained.…”

Section: Resultsmentioning

confidence: 83%

Divergent Synthesis of Bioactive Marine Meroterpenoids by Palladium‐Catalyzed Tandem Carbene Migratory Insertion

Wang

Zhang

2018

Eur J Org Chem

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The divergent synthesis of (+)‐8‐epi‐puupehedione, (+)‐chromazonarol, (+)‐yahazunol, and (+)‐yahazunone has been accomplished. The key steps were a palladium‐catalyzed tandem carbene migratory insertion of an aryl iodide and a drimanal hydrazone, a highly regioselective enol reduction, an oxa‐Stork–Danheiser transposition reaction, an electrocyclization of a conjugated tetraenone, and a redox reaction of dimethoxybenzenes.

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Diastereoselective Palladium-Catalyzed Formate Reduction of Allylic Carbonates en Route to Polypropionate Systems

Cited by 31 publications

References 50 publications

Enantioselective semireduction of allenes

Enantioselective semireduction of allenes

Total Synthesis of (−)‐Zampanolide and Structure–Activity Relationship Studies on (−)‐Dactylolide Derivatives

Divergent Synthesis of Bioactive Marine Meroterpenoids by Palladium‐Catalyzed Tandem Carbene Migratory Insertion

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