Alkylboronic Suzuki coupling

In addition, with respect to the Suzuki coupling, various alkylboron reagents have also been successfully coupled with electrophile partners. 

While the introduction of aryl groups has been well documented, the use of alkylboronic acids to decorate the pyridazine core is hitherto not well explored. Wermuth and co-workers nicely showed that hydroboration of alkenes with 9-BBN followed by Suzuki coupling with 3-iodopyridazines 180 and 182 yielded the corresponding 3-alkylpyr-idazines 181 and 183 in good yield (Schemes 43 and 44) <2002SL1123>. 

Keywords iodobenzene, alkylboronic acid, Suzuki coupling, palladium-doped... 

Arylethylamines. The title compound is transformed into an alkylboronic acid via hydroboration and its Suzuki coupling with Arl affords ArCH2CH2NHCbz. 

As in the Negishi reaction, various alkylboron reagents have also been successfully coupled with electrophile partners. Suzuki et al. coupled 1-bromo-l-phenylthioethene with 9-[2-(3-cyclohexenyl)ethyl]-9-BBN (27), prepared by a simple addition of 9-borabicyclo[3.3.1]nonane (9-BBN) to 4-vinyl-1-hexene (26), to furnish 4-(3-cyclohexenyl)-2-phenylthio-1-butene (28) in good yield [36],... 

Cross-coupling reactions 5-alkenylboron boron compounds, 9, 208 with alkenylpalladium(II) complexes, 8, 280 5-alkylboron boron, 9, 206 in alkyne C-H activations, 10, 157 5-alkynylboron compounds, 9, 212 5-allylboron compounds, 9, 212 allystannanes, 3, 840 for aryl and alkenyl ethers via copper catalysts, 10, 650 via palladium catalysts, 10, 654 5-arylboron boron compounds, 9, 208 with bis(alkoxide)titanium alkyne complexes, 4, 276 carbonyls and imines, 11, 66 in catalytic C-F activation, 1, 737, 1, 748 for C-C bond formation Cadiot-Chodkiewicz reaction, 11, 19 Hiyama reaction, 11, 23 Kumada-Tamao-Corriu reaction, 11, 20 via Migita-Kosugi-Stille reaction, 11, 12 Negishi coupling, 11, 27 overview, 11, 1-37 via Suzuki-Miyaura reaction, 11, 2 terminal alkyne reactions, 11, 15 for C-H activation, 10, 116-117 for C-N bonds via amination, 10, 706 diborons, 9, 167... 

Alkylboronic acids and arylboronic acids, RB(OH)2, and ArB(OH)2, respectively, are increasingly important in organic chemistry. The palladium catalyzed coupling reaction of aryl halides and aryl triflates with arylboronic acids (the Suzuki-Miyaura... 

Alkylboronic acids are coupled to aryl halides using a palladium catalyst, " analogous to the Suzuki reaction in 13-12. Conversely, arylboronic acids can be coupled to aliphatic halides Arylboronic acids can be coupled to allylic alcohols as well. " Arylboronic acids (12-28) were shown to react directly with benzene in the presence of Mn(OAc)3. " Arylboronic acids also couple with alkyl halides in... 

Suzuki-Miyaura cross-coupling reactions of alkylboronic acid derivatives or alkyltrifluoroborates widi aryl, alkenyl or alkyl halides and triflates ,... 

Suzuki-Miyaura Cross-Coupling Reactions of Alkylboronic Acid Derivatives or Alkyltrifluoroborates with Aryl, Alkenyl or Alkyl Halides and Triflates Doucet, H. Eur. J. Org. Chem. 2008, 2013. 

Alkenylboronic acids and esters are also very useful substrates (Equation 71, Figure 1.38) [405], in particular to access substituted olefins and dienyl moieties commonly encountered in several classes of bioactive natural products [282, 406]. To this end, Kishi and co-workers examined the influence of the base, and developed an optimal variant using thallium hydroxide [281]. Recently, allylic alcohols were found to couple directly with alkyl and alkenyl boronic acids without the aid of a base [407]. In rare cases, the Suzuki reaction has been applied to the use of alkylboronic acids [296, 408], including cyclopropylboronic acids [409]. Hitherto notorious for their tendency to undergo [3-hydride elimination, alkyl bromides are now suitable as electrophiles under carefully optimized conditions that even allow Csp -Csp couplings with alkylboronic acids (Equation 72) [410]. The Suzuki reaction has also been applied very successfully in solid-phase chemistry and combinatorial library synthesis [411]. It has been applied industrially [412], especially in medicinal chemistry, e.g. in the production of the antihypertensive drug losartan [195]. 

Keywords Allyl bromides, benzyl bromides, diborylmethane derivative, Pd-catalysts such as [Pd-PEPPSI-IPr] (l)/Pd[P(f-Bu)3l2 (2), aq. KOH, dioxane, room temperature, Suzuki-Miyaura cross-coupling (SMC) reaction, C-C bond formation, regio- and chemoseletivity, homoallylboronates, alkylboronates... 

Abe, S. Miyaura, N. Suzuki, A. 1992. The palladium-catalyzed cross-coupling reaction of enol acetates of a-bromo ketones with 1-alkenyl-, aryl-, or alkylboron compounds A facile synthesis of ketones and their enol acetates. J. Am. Chem. Soc. 65 2863-2865. 

Cross-coupling of Boronic Acids. Ag20 can significantly enhance the reactivity of various boronic acids in Suzuki-Miyaura cross-coupling reactions. Alkylboronic acids, which, oftentimes, lead to poor conversions of the desired coupled product, are rendered more reactive by the addition of Ag20 (eq 24). Use of excess Ag20 facilitates the cross-coupling of various unactivated w-alkylboronic acids to either aryl or alkenyl halides/trifiates. The reaction conditions are very mild and furnish excellent yields of the desired coupled product. 

Scheme 3.84 Ag(l)-promoted Suzuki-Miyaura cross-coupling of functionalized n-alkylboronic acids.

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