Stereopentads Derived from a Sequence of Mukaiyama Aldolization and Free Radical Reduction on α-Methyl-β-alkoxy Aldehydes: A General Strategy for Efficient Polypropionate Synthesis

Brazeau, Jean-Francois; Mochirian, Philippe; Prévost, Michel; Guindon, Yvan

doi:10.1021/jo8021583

Cited by 28 publications

(11 citation statements)

References 81 publications

(41 reference statements)

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“…Diastereodivergent aldol reactions have been carried out with α-methyl-β-alkoxy aldehydes such as 71 by adding a mixture of E and Z -enolsilanes 72 derived from 2-bromopropionate in the presence of different Lewis acids . A high 3,4- syn diastereoselectivity was observed when the monodentate Lewis acid BF 3 ·OEt 2 was used giving esters 73 .…”

Section: Stereodivergence In Acyclic Systemsmentioning

confidence: 99%

Stereodivergent Catalysis

2018

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This review covers diastereo- and enantiodivergent catalyzed reactions in acyclic and cyclic systems using metal complexes or organocatalysts. Among them, nucleophilic addition to carbon-carbon and carbon-nitrogen double bonds, α-functionalization of carbonyl compounds, allylic substitutions, and ring opening of oxiranes and aziridines are considered. The diastereodivergent synthesis of alkenes from alkynes is also included. Finally, stereodivergent intramolecular and intermolecular cycloadditions and other cyclizations are also reported.

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Section: Stereodivergence In Acyclic Systemsmentioning

confidence: 99%

Stereodivergent Catalysis

2018

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“…The reaction sequence to generate the targeted family of nucleoside analogues began with construction of the all-carbon quaternary center (Scheme 2). The key precursor 8a,b for the intramolecular radical atom transfer cyclization was efficiently accessed by a three-step sequence involving a Mukaiyama aldol reaction 16,17 between 2,3-isopropylidene-D-glyceraldehyde 9 and enoxysilanes 10 in the presence of MgBr2 . OEt2.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of nucleoside analogues using acyclic diastereoselective reactions

Lussier¹,

Waltz²,

Freure³

et al. 2019

Arkivoc

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The design of novel xylo-like nucleoside analogues bearing a C3' all-carbon quaternary center and a C2'hydroxy substituent is described. Synthesis of this scaffold makes use of highly diastereoselective transformations on acyclic substrates. Central to the approach is formation of a 2,4-syn cyanohydrin from cyanide addition onto an aldehyde through a proposed seven-membered ring chelate using a bidentate Lewis acid. In addition, a highly diastereoselective Mukaiyama aldol reaction, an intramolecular radical atom cyclization, and thioaminal formation are used to generate this novel molecule. A series of related nucleoside analogues are being tested as antiviral and anticancer agents.

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“…Inspired by the work of Guindon and co-workers, atom-transfer experiments with α-bromo β-hydroxy ester 45 were conducted (Scheme ). , They were able to generate aluminum chelated radical intermediates with AlMe 3 and trapped them with Bu 3 SnH or allylTMS/allylSnBu 3 to generate reduced or allylated products with excellent diastereoselectivity. These conditions were employed, without addition of the reductant/nucleophile, on α-bromo β-hydroxy ester 45 to generate the aluminum chelated intermediate.…”

Section: Resultsmentioning

confidence: 99%

Toward a Unified Total Synthesis of the Xiamycin and Oridamycin Families of Indolosesquiterpenes

Trotta

2017

J. Org. Chem.

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A unified synthetic strategy toward the oridamycin and xiamycin families of natural products was designed, aiming to access several natural products from a common synthetic intermediate readily prepared from geranyl acetate. Part of this strategy was successfully realized, culminating in the synthesis of oridamycin A and oridamycin B. Key steps include a Mn(III)-mediated oxidative radical cyclization to construct the trans-decalin ring, and a 6π-electrocyclization/aromatization sequence to produce the 2,3-fused carbazole. Oridamycin B was accessed through a late-stage, C-H oxidation that converted the C16 methyl to a hydroxymethyl. A variety of strategies were explored to form a chelated radical intermediate en route to xiamycin A, including enolate SET oxidation, oxo-vanadium oxidation, and atom-transfer cyclization. Unfortunately, none of these strategies provided the desired C16-epimeric trans-decalin. Exploratory studies on photoredox-catalyzed radical cyclizations yielded interesting results, including the formation of a bicyclic lactone arising from oxidative termination of the photoredox-catalyzed radical cyclization, and a double 6-endo cyclization with catalyst loadings as low as 0.01 mol%.

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Stereopentads Derived from a Sequence of Mukaiyama Aldolization and Free Radical Reduction on α-Methyl-β-alkoxy Aldehydes: A General Strategy for Efficient Polypropionate Synthesis

Cited by 28 publications

References 81 publications

Stereodivergent Catalysis

Stereodivergent Catalysis

Synthesis of nucleoside analogues using acyclic diastereoselective reactions

Toward a Unified Total Synthesis of the Xiamycin and Oridamycin Families of Indolosesquiterpenes

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