On the choice of Lewis acids for the Prins reaction; two total syntheses of (±)-Civet

Chio, Freda K. I.; Warne, Julie; Gough, Damien Francis Christopher; Penny, Mark J.; Green, Sasa; Coles, Simon J.; Hursthouse, M. B.; Jones, Peter; Hassall, Lorraine; McGuire, Thomas M.; Dobbs, Adrian P.

doi:10.1016/j.tet.2011.05.019

Cited by 55 publications

(28 citation statements)

References 56 publications

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“…These two types of product may both be formed during the reaction and the selectivity depends on the reaction conditions, especially the type of catalyst [3]. Lewis [4][5][6][7] or Brønsted acids (inorganic [1,8], organic [9], or ion exchangers [10,11]) may be used as catalysts; occasionally, heteropolyacids [12], organometallic complexes [13] or heterogeneous aluminosilicates [14] are used. The accepted mechanism [15] involves hemiacetal formation in the first step followed by cyclization to form the substituted tetrahydropyranol or dihydropyrans (Fig.…”

Section: Introductionmentioning

confidence: 99%

Contribution to elucidation of the mechanism of preparation of 2-isobutyl-4-methyltetrahydro-2H-pyran-4-ol

et al. 2015

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The effects of catalyst type (sulfuric acid, Amberlyst 15, p-toluenesulfonic acid, and p-dodecylbenzenesulfonic acid) and of addition of water on the preparation of 2-isobutyl-4-methyltetrahydro-2H-pyran-4-ol by Prins cyclization were studied. It was discovered that in the absence of added water the amphiphilic character of the acid had the main effect and that organic acids were unsuitable for preparation of this compound. From the perspective of the ratio of the amount of the desired product to that of dihydropyrans, after addition of water the results obtained by use of p-toluenesulfonic acid (ratio 3.5, selectivity 67 %) were comparable with those obtained by use of sulfuric acid and were better than those obtained by use of Amberlyst 15 (ratio 2.3, selectivity 68 %). A detailed study of the mechanism confirmed that addition of water to the double bonds of dihydropyrans does not occur.

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Section: Introductionmentioning

confidence: 99%

Contribution to elucidation of the mechanism of preparation of 2-isobutyl-4-methyltetrahydro-2H-pyran-4-ol

et al. 2015

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“…For example, treatment of 2‐[4‐(trifluoromethyl)phenethyl]but‐3‐en‐1‐ol with benzaldehyde gave the desired product in very low yield (< 10 %) under similar conditions. Unlike the reported method, no dihydropyran was formed under our reaction conditions 3j…”

Section: Resultsmentioning

confidence: 76%

The Prins Cascade Cyclization Reaction for the Synthesis of Angularly‐Fused Tetrahydropyran and Piperidine Derivatives

et al. 2013

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2‐Arylethylbut‐3‐en‐1‐ol is found to undergo smooth Prins cascade reactions with various aldehydes in the presence of Sc(OTf)3 (10 mol‐%) and a stoichiometric amount of TsOH to afford the corresponding trans‐fused hexahydro‐1H‐benzo[f]isochromenes in good yields with excellent selectivity. Likewise, N‐tosyl‐2‐phenethylbut‐3‐en‐1‐amine gives trans‐fused octahydrobenzo[f]isoquinoline derivatives under similar conditions. This is the first example of the synthesis of hexahydro‐1H‐benzo[f]isochromene and octahydrobenzo‐[f]isoquinoline from 2‐arylethylbut‐3‐en‐1‐ol and N‐tosyl‐2‐phenethylbut‐3‐en‐1‐amine, respectively.

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“…This positive result marks the first example of an enantioselective method to generate oxazinoindoles and is only the second example of an enantioselective oxa-Pictet-Spengler reaction. [11] In summary, a mild and efficient process to generate a wide variety of heterocycle-fused indoles has been developed utilizing cooperative catalysis between an iridium(III) catalyst and Bi(OTf) 3 . Three distinct cyclization manifolds (Types 1-3) lead to bioactive scaffolds which can be obtained in good yields through a one-pot reaction with low catalyst loadings while avoiding the traditional harsh reaction conditions of Prins-type reactions.…”

Section: Methodsmentioning

confidence: 99%

“…Protonations of enol ethers have also been used independently by the groups of Rychnovsky and Dobbs to promote Prins cyclizations with vinyl and allyl silanes. [11] Notably, the construction of the pyran 4 would be possible at ambient temperatures and without the use of carbonyl functional groups.…”

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confidence: 99%

A Tandem Isomerization/Prins Strategy: Iridium(III)/Brønsted Acid Cooperative Catalysis

2013

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In Gemeinschaftsarbeit: Eine milde und effiziente Isomerisierungs‐Protonierungs‐Sequenz unter kooperativer Katalyse durch kationische Iridium(III)‐Spezies und Bi(OTf)3 ergibt Pyran‐anellierte Indole. Drei verschiedene Cyclisierungsarten führen in guten Ausbeuten zu den entsprechenden Gerüsten von biologisch aktiven Substanzen. In Gegenwart eines chiralen Phosphats sind auch N‐substituierte Indole enantioselektiv zugänglich.

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On the choice of Lewis acids for the Prins reaction; two total syntheses of (±)-Civet

Cited by 55 publications

References 56 publications

Contribution to elucidation of the mechanism of preparation of 2-isobutyl-4-methyltetrahydro-2H-pyran-4-ol

Contribution to elucidation of the mechanism of preparation of 2-isobutyl-4-methyltetrahydro-2H-pyran-4-ol

The Prins Cascade Cyclization Reaction for the Synthesis of Angularly‐Fused Tetrahydropyran and Piperidine Derivatives

A Tandem Isomerization/Prins Strategy: Iridium(III)/Brønsted Acid Cooperative Catalysis

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