A stereoselective synthesis of cis-alkenylboranes

Negishi, Ei‐ichi; Williams, Robert M.; Lew, George; Yoshida, Takao

doi:10.1016/s0022-328x(00)91110-0

Cited by 56 publications

(19 citation statements)

References 16 publications

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“…52 The resulting 1-halo-1-alkenylborane was treated with sodium methoxide, which triggered a 1,2-alkyl shift from boron to the vinylic center (also termed a 1,2-metallate rearrangement) 53,54. Other nucleophiles such as Grignard reagents (B),55,56 alkyllithiums (B),55,56 and hydrides (C)57–59 also initiated similar 1,2-metallate rearrangements. The resulting ( E ) - vinylboranes are fairly unreactive and thus were either oxidized to ketones or protodeborated under acidic conditions to afford trans -alkenes (Scheme 4, A).…”

Section: Resultsmentioning

confidence: 96%

One-Pot Multicomponent Coupling Methods for the Synthesis of Diastereo- and Enantioenriched (Z)-Trisubstituted Allylic Alcohols

et al. 2009

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Abstract(Z)-Trisubstituted allylic alcohols are widespread structural motifs in natural products and biologically active compounds but are difficult to directly prepare. Introduced herein is a general one-pot multicomponent coupling method for the synthesis of (Z)-α,α,β-trisubstituted allylic alcohols. (Z)-Trisubstituted vinylzinc reagents are formed in situ by initial hydroboration of 1-bromo-1-alkynes. Addition of dialkylzinc reagents induces a 1,2-metallate rearrangement that is followed by a boron-to-zinc transmetallation. The resulting vinylzinc reagents add to a variety of prochiral aldehydes to produce racemic (Z)-trisubstituted allylic alcohols. When enantioenriched aldehyde substrates are employed (Z)-trisubstituted allylic alcohols are isolated with high dr (>20:1 in many cases). For example, vinylation of enantioenriched benzyl protected α-and β-hydroxy propanal derivatives furnished the expected anti-Felkin addition products via chelation control. Surprisingly, silyl protected α-hydroxy aldehydes also afford anti-Felkin addition products. A protocol for the catalytic asymmetric addition of (Z)-trisubstituted vinylzinc reagents to prochiral aldehydes with a (−)-MIB-based catalyst has also been developed. Several additives were investigated as inhibitors of the Lewis acidic alkylzinc halide byproducts, which promote the background reaction to form the racemate. α-Ethyl and α-cyclohexyl (Z)-trisubstituted allylic alcohols can now be synthesized with excellent levels of enantioselectivity in the presence of diamine inhibitors.

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Section: Resultsmentioning

confidence: 96%

One-Pot Multicomponent Coupling Methods for the Synthesis of Diastereo- and Enantioenriched (Z)-Trisubstituted Allylic Alcohols

et al. 2009

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“…In cases where 1-halo-1-alkynes are used as internal alkynes, the reaction is nearly 100% regioselective placing B at the halogen-bound carbon. The resultant (Z)-α-haloalkenylboranes can be used to prepare (i) (Z)-1-alkenylboranes (Type IV) [59], (ii) (Z)-α,β-disubstituted alkenylboranes (Type V) [60], and (iii) (E)-α,β-disubstituted alkenylboranes (Type VI) [61] as summarized in Scheme 3.9.…”

Section: Element-metal Bonds (E-m)mentioning

confidence: 99%

“…On the other hand, Type IV alkenyl derivatives may be prepared by: (i) Normant alkylcupration of ethyne [67,68] (Eqs. (5) and (6), Scheme 3.11), (ii) Zr-catalyzed alkylalumination of ethyne, (iii) syn hydroboration of 1-halo-1-alkynes followed by hydride-induced inversion of configuration [59] (Scheme 3.9), (iv) hydroboration of 1-alkynes followed by brominolysis (but not iodinolysis) with inversion [95], and (v) syn hydrozirconation or syn hydroalumination of 1-boryl-or 1-silyl-1-alkynes followed by protonolysis of the C-Al or C-Zr bond [96][97][98].…”

Section: Aryl-alkenyl and Alkenyl-aryl Couplingsmentioning

confidence: 99%

“…It does appear reasonably certain that, as long as the requisite Types IX and X alkenyl reagents can be obtained in the y(es) 2 manner, Pd-catalyzed alkenylation, especially by the Negishi version, will provide a wide range of tetrasubstituted alkenes of defined regio-and stereochemistry. Even though there is still some room for improvement, evolutionary development of Suzuki alkenylation through rational optimization of several changeable parameters including (i) borane and borate ligands (BY 2 and BY 3 M) [106], (ii) Pd catalysts [150], (iii) added promoters, and (iv) solvent compositions, and others has been continuously improving the mysteriously multitalented boron-based protocol [55][56][57][58][59][60][61][62]. As representative examples of recent developments of tetrasubstituted alkene syntheses in the y(es) 2 manner, the following two routes to the anticancer agent (Z)-tamoxifen, one by Ni-catalyzed carbozincation-Negishi coupling [151] and the other by Cu-catalyzed carbomagnesiation-Suzuki coupling [152] are shown in Scheme 3.36.…”

Section: Tetrasubstituted Alkenes Via Types IX and X Alkenyl Reagentsmentioning

confidence: 99%

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Pd‐Catalyzed Cross‐Coupling with Organometals Containing Zn, Al, Zr, and so on – The Negishi Coupling and Its Recent Advances

Kamada

Kim

et al. 2013

Metal‐Catalyzed Cross‐Coupling Reactions and More

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The Pd-or Ni-catalyzed cross-coupling reactions of organometals containing Zn, Al, Zr, and B as well as related reactions of those containing Mg and several other metals collectively have emerged as arguably the most widely applicable organic skeleton construction method discovered and developed over the past several decades, allowing synthetic chemists to prepare practically all types of organic compounds. In this chapter, some of the seminal and critically important discoveries and early developments in the 1970s as well as their current scope are briefly discussed. Some of the notable discoveries and developments include (i) identification of superior properties of Pd as a critical element for crosscoupling relative to Ni, (ii) the broad scope of Pd-or Ni-catalyzed cross-coupling with respect to metal countercations including Zn, Al, Zr, B, and Mg, (iii) the hydrometallation-Pd-catalyzed cross-coupling sequential processes for selective syntheses of alkenes, dienes, oligoenes, and oligoenynes, (iv) double metal catalysis involving Pd or Ni and added metal compounds containing Zn, In, Li, and others, and (v) realization of high turnover numbers (TONs) (≥10 3 -10 9 ) through the use of chelating phosphines, such as bis-[2-(diphenylphosphino)phenyl] ether (DPEphos) and 1,1 -Bis(diphenylphosphino)ferrocene (dppf).The Zr-catalyzed alkyne carboalumination and the Zr-catalyzed asymmetric carboalumination of alkenes (ZACA reaction) have provided efficient and selective routes to (E)-trisubstituted alkenylalanes and 2-substituted chiral alkylalanes, respectively. These reactions provide two additional examples of prototypical transition metal-catalyzed organometallic reactions. Significantly, they can be readily combined with the Pd-or Ni-catalyzed cross-coupling for the synthesis of trisubstituted alkenes embracing a wide variety of natural products, such as terpenoids, carotenoids, and others, as well as various chiral organics including deoxypolypropionates and saturated terpenoids. The Zr-catalyzed alkyne carboalumination has been applied to the synthesis of a large number (>100) of natural products, while the ZACA reaction has been transformed from a mere scientific novelty to a full-fledged asymmetric synthetic method that is catalytic in both transition metal (Zr) and chiral auxiliaries through a series of breakthroughs.

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“…16 Thus, 4 was subjected to the reaction with (trimethylsilyl)ethynyl bromide under the same conditions as described above ( Table 3). The reactions using (Z)-alk-1-enyldisiamylborane and NaOMe led to the selective formation of (Z)-alk-3-en-1-yne (5) in satisfactory yields ( Table 3, entries 1-5) and tolerated a number of functional groups.…”

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confidence: 99%

Construction of Terminal Conjugated Enynes: Cu-Mediated Cross-Coupling Reaction of Alkenyldialkylborane with (Trimethylsilyl)ethynyl Bromide

Hoshi¹,

Kawamura²,

Shirakawa³

2006

Synthesis

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The cross-coupling reaction of (E)-and (Z)-alk-1-enyldialkylborane with (trimethylsilyl)ethynyl bromide proceeds in the presence of a catalytic amount of copper(II) acetylacetonate and a base under extremely mild conditions to provide conjugated enynes with a distal carbon-carbon triple bond. Employing sodium methoxide (1 M) as the base results in not only cross-coupling but also desilylation affording both (E)-and (Z)-alk-3-en-1-ynes, exclusively, while lithium hydroxide monohydrate gives both (E)-and (Z)-1-(trimethylsilyl)alk-3-en-1-ynes with high regio-and stereoselectivity. On the other hand, the cross-coupling reaction of (Z)-1-(trimethylsilyl)alk-1-enyldicyclohexylborane with (trimethylsilyl)ethynyl bromide proceeds in the presence of a small amount of copper(I) iodide and aqueous sodium hydroxide under extremely mild conditions to afford (Z)-1,3-bis(trimethylsilyl)alk-3-en-1-yne with high regio-and stereoselectivity. In addition, treatment of the resulting product with sodium methoxide (1 M) leads to the stereoselective formation of (Z)-3-(trimethylsilyl)alk-3-en-1-yne in a one-pot synthesis.

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A stereoselective synthesis of cis-alkenylboranes

Cited by 56 publications

References 16 publications

One-Pot Multicomponent Coupling Methods for the Synthesis of Diastereo- and Enantioenriched (Z)-Trisubstituted Allylic Alcohols

One-Pot Multicomponent Coupling Methods for the Synthesis of Diastereo- and Enantioenriched (Z)-Trisubstituted Allylic Alcohols

Pd‐Catalyzed Cross‐Coupling with Organometals Containing Zn, Al, Zr, and so on – The Negishi Coupling and Its Recent Advances

Construction of Terminal Conjugated Enynes: Cu-Mediated Cross-Coupling Reaction of Alkenyldialkylborane with (Trimethylsilyl)ethynyl Bromide

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