Triethylborane

Yamamoto, Yoshinori; Yoshimitsu, Takehiko; Wood, John L.; Schacherer, Laura

doi:10.1002/9780470842898.rt219.pub3

Cited by 2 publications

(2 citation statements)

References 196 publications

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“…Initial studies explored the effect of the Lewis acid trimethyl borate as a reaction additive owing to its chemically benign character compared with the pyrophoricity and radical reactivity associated with alkylboranes. 26 The initial investigation began by evaluating the effect of trimethyl borate on the Suzuki− Miyaura cross-coupling of 2-(4-bromophenyl)-1,3,4-oxadiazole 1b. This heteroaromatic electrophile was previously found to be unreactive under our optimized reaction conditions when paired with neopentyl 4-fluorophenylboronic ester 2a.…”

Section: ■ Resultsmentioning

confidence: 99%

Heteroaryl–Heteroaryl, Suzuki–Miyaura, Anhydrous Cross-Coupling Reactions Enabled by Trimethyl Borate

et al. 2021

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Reaction conditions have been developed for refractory heteroaryl–heteroaryl Suzuki–Miyaura cross-couplings. The reported method employs neopentyl heteroarylboronic esters as nucleophiles, heteroaryl bromides and chlorides as the electrophiles, and the soluble base potassium trimethylsilanolate (TMSOK) under anhydrous conditions. The addition of trimethyl borate enhances reaction rates by several mechanisms, including (1) solubilization of in situ-generated boronate complexes, (2) preventing catalyst poisoning by the heteroatomic units, and (3) buffering the inhibitory effect of excess TMSOK. The use of this method enables cross-coupling of diverse reaction partners including a broad range of π-rich and π-deficient heteroaryl boronic esters and heteroaryl bromides. Reactions proceed in good yields and short reaction times (3 h or less).

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Section: ■ Resultsmentioning

confidence: 99%

Heteroaryl–Heteroaryl, Suzuki–Miyaura, Anhydrous Cross-Coupling Reactions Enabled by Trimethyl Borate

et al. 2021

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“… 14,42 Although our method unfortunately was not compatible with the direct preparation of alkenylsulfide bromomethyl derivatives (see Table 1 ), we could demonstrate exceptional reactivity of α-thiomethyl radical 7k (generated from 2k), towards (TMS) 3 SiH reduction, 43 thus generating thioether 8k ( Scheme 4a ). On the other hand, Et 3 B initiated 44 additions of nucleophilic radicals 40,45 7f and 7k on radical acceptors acrylonitrile and methyl acrylate led to the generation of γ-functionalized sulfides 9f, 9k, 10f and 10k ( Scheme 4b ). This constitutes a novel approach for the synthesis of γ-sulfanyl butanenitriles and esters, as an alternative to the thiol-ene reaction approach, 46 and establishes bromomethyl sulfides as a new entry on the family of monothiomethyl radical sources.…”

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confidence: 99%