Oxidative Heck Arylation for the Stereoselective Synthesis of Tetrasubstituted Olefins Using Nitroxides as Oxidants

He, Zhiheng; Kirchberg, Sylvia; Fröhlich, Roland; Studer, Armido

doi:10.1002/anie.201108211

Cited by 124 publications

(43 citation statements)

References 50 publications

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“…Utilizing the method for step [h] (Scheme ), methylation of ( E )‐ 20 and ( Z )‐ 20 using MeLi/CuI proceeded smoothly to yield the corresponding fully substituted olefins ( E )‐ 21 and ( Z )‐ 21 (conditions [c] and [h]). A notable advantage of the present method is the reduced number of steps compared with reported transformations (Dess–Martin oxidation, Wittig methylene formation, and catalytic hydrogenation).…”

Section: Resultsmentioning

confidence: 99%

“…159–160 °C (Ref. : 161 °C); 1 H NMR (500 MHz, CDCl 3 ): δ =1.49 (t, J= 5.7 Hz, 1 H), 3.83 (s, 3 H), 4.51 (d, J= 5.7 Hz, 2 H), 6.85–6.96 (m, 4 H), 7.00–7.08 (m, 3 H), 7.10–7.22 (m, 4 H), 7.23–7.30 ppm (m, 3 H); 13 C NMR (125 MHz, CDCl 3 ): δ =55.2, 65.1, 113.5 (2C), 126.4, 126.7, 127.4 (2C), 128.1 (2C), 129.9 (2C), 130.7 (2C), 130.9 (2C), 134.6, 137.9, 140.5, 142.5, 142.6, 158.8 ppm; IR (neat):

\overset{ν}{true}

max =3536, 1603, 1574, 1506, 1439, 1358, 1306, 1236, 1180 cm −1 .…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Divergent Synthetic Access toE- andZ-Stereodefined All-Carbon-Substituted Olefin Scaffolds: Application to Parallel Synthesis of (E)- and (Z)-Tamoxifens

et al. 2017

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A highly substrate‐general synthesis of all‐carbon‐substituted E‐ and Z‐stereodefined olefins is performed. The method comprises two sets of parallel and stereocomplementary preparations of (E)‐ and (Z)‐α,β‐unsaturated esters involving two robust and distinctive reactions: 1) stereocomplementary enol tosylations using readily available TsCl/diamine/(LiCl) base reagents, and 2) stereoretentive Negishi cross‐coupling using the catalysts [Pd(dppe)Cl2] (for E) and [Pd(dppb)Cl2] (for Z). The present parallel approach is categorized as both type I (convergent approach: 16 examples, 56–87 % yield) and type II (divergent approach: 18 examples, 70–95 % yield). The obtained (E)‐ and (Z)‐α,β‐unsaturated ester scaffolds are successfully transformed into various E‐ and Z‐stereodefined known and novel olefins (8×2 derivatization arrays). As a demonstration, application to the parallel synthesis of both (E)‐ and (Z)‐tamoxifens, a representative motif of all‐carbon‐substituted olefins, is accomplished in a total of eight steps with an overall yield of 58 % (average 93 %) and 57 % (average 93 %), respectively.

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Section: Resultsmentioning

confidence: 99%

\overset{ν}{true}

max =3536, 1603, 1574, 1506, 1439, 1358, 1306, 1236, 1180 cm −1 .…”

Section: Methodsmentioning

confidence: 99%

Divergent Synthetic Access toE- andZ-Stereodefined All-Carbon-Substituted Olefin Scaffolds: Application to Parallel Synthesis of (E)- and (Z)-Tamoxifens

et al. 2017

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“…10,11 Classical synthetic methods including Wittig, 12 Horner–Wadsworth–Emmons (HWE), 12 Julia, 13 Peterson, 14 and McMurry 15 reactions generally afford poor stereoselectivities. Eliminations of highly functionalized tertiary alcohols produce tetrasubstituted olefins; 16 however, the synthesis of the alcohol precursors is often challenging, and multiple elimination pathways frequently result in erosion of stereocontrol.…”

Section: Introductionmentioning

confidence: 99%

Highly Stereoselective Synthesis of Tetrasubstituted Acyclic All-Carbon Olefins via Enol Tosylation and Suzuki–Miyaura Coupling

Li¹,

Le²,

Mack

et al. 2017

J. Am. Chem. Soc.

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A highly stereocontrolled synthesis of tetrasubstituted acyclic all-carbon olefins has been developed via a stereoselective enolization and tosylate formation, followed by a palladium-catalyzed Suzuki–Miyaura cross-coupling of the tosylates and pinacol boronic esters in the presence of Pd(OAc)2/RuPhos catalytic system. Both the enol tosylation and Suzuki–Miyaura coupling reactions tolerate an array of electronically and sterically diverse substituents and generate high yield and stereoselectivity of the olefin products. Judicious choice of substrate and coupling partner provides access to either E- or Z-olefin with excellent yield and stereochemical fidelity. Olefin isomerization was observed during the Suzuki–Miyaura coupling. However, under the optimized cross-coupling reaction conditions, the isomerization was suppressed to <5% in most cases. Mechanistic probes indicate that the olefin isomerization occurs via an intermediate, possibly a zwitterionic palladium carbenoid species.

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“…Moreover, no bis-arylated product is formed when the monoarylated substrate is subjected to either our best reaction conditions (Scheme 4) or those reported for oxidative Heck reactions, where (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) was added as the oxidizing agent [36] (Scheme 5). Therefore, it seems like this process proceeds through a concomitant C-Br=C-H double arylation on methyl 4-bromocrotonate rather than the two-step pathway depicted in Scheme 3 and that this process is in competition with the monoarylation reaction (Scheme 3).…”

Section: Discussionmentioning

confidence: 98%

Nickel-Catalyzed C-Br/C-H Bis-phenylation of Methyl 4-Bromocrotonate: A Stereoselective Entry to Methyl (E)-3,4-Diphenylbut-2-enoate

Funicello

Chiummiento

Lupattelli

et al. 2015

Synthetic Communications

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Oxidative Heck Arylation for the Stereoselective Synthesis of Tetrasubstituted Olefins Using Nitroxides as Oxidants

Cited by 124 publications

References 50 publications

Divergent Synthetic Access toE- andZ-Stereodefined All-Carbon-Substituted Olefin Scaffolds: Application to Parallel Synthesis of (E)- and (Z)-Tamoxifens

Divergent Synthetic Access toE- andZ-Stereodefined All-Carbon-Substituted Olefin Scaffolds: Application to Parallel Synthesis of (E)- and (Z)-Tamoxifens

Highly Stereoselective Synthesis of Tetrasubstituted Acyclic All-Carbon Olefins via Enol Tosylation and Suzuki–Miyaura Coupling

Nickel-Catalyzed C-Br/C-H Bis-phenylation of Methyl 4-Bromocrotonate: A Stereoselective Entry to Methyl (E)-3,4-Diphenylbut-2-enoate

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