Methods for the homologation of benzofurancarboxylic acids using dianionic intermediates

Buttery, Cheryl D.; Knight, David W.; Nott, Andrew P.

doi:10.1016/s0040-4039(00)88366-5

Cited by 15 publications

(3 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…But the two nitrogen surrounding Hb prevent bulky LDA from approaching it. Intermediate VI , formed by the ring opening of intermediate V , yields 4 a quenched with H 2 O (Scheme 2, par a) [12a,21] . For part b, initially, alkyne nucleophile 5 a attacks C‐4 of quinazoline [11a] .…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Transition‐Metal‐Free Synthesis of 4‐Alkynylquinazolines

Uçar

Daştan

2022

Eur J Org Chem

View full text Add to dashboard Cite

Protocols have been developed that allow easy access to 4alkynylquinazolines under transition-metal-free conditions. The ring opening reaction of 4-(benzofuran-2-yl)quinazolines obtained from the arylation of quinazolines with benzofuran is the first way to achieve 4-alkynylquinazolines. Direct alkynylation of quinazolines with terminal alkynes in the presence of n-BuLi and iodine or with alkynyl Grignard reagents is another strategy. Desilylation of 4-((trimethylsilyl)ethynyl)quinazolines obtained by direct alkynation is the third approach to give 4alkynylquinazolines. It has also been shown that the protocols are applicable for scale-up synthesis.

show abstract

Section: Resultsmentioning

confidence: 99%

“…It is also known that benzofuran gives 2-ethynylphenol with an ring opening reaction in basic medium. [12] We thought that this reaction would also be a great alternative to achieve 4-alkynylquinazolines (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Transition‐Metal‐Free Synthesis of 4‐Alkynylquinazolines

Uçar

Daştan

2022

Eur J Org Chem

View full text Add to dashboard Cite

show abstract

“…Lithiation of benzofuran-3-carboxylic acid (44) with LDA in THF at -78 °C gave the corresponding 2-lithio reagent 45, which on reaction with various electrophiles gave the corresponding 2-substituted derivatives 46 (Scheme 16) in 75-100% yields. 215,216 Lithiation of benzofuran-2-carboxylic acid took place at the 3-position. 216 i, Electrophile In contrast, lithiation of 47 with t-BuLi (2.0 equivalents) in the absence of TMEDA in THF at -20 °C, followed by cyanation, took place at the C-5 position to give 5-substituted derivative 51 in 71% yield via formation of lithium reagent 50 (Scheme 18).…”

Section: Directed Ortho-lithiation Of Other Heterocyclesmentioning

confidence: 99%

Directed lithiation of simple aromatics and heterocycles for synthesis of substituted derivatives

El‐Hiti¹,

Smith²,

Hegazy³

et al. 2014

Arkivoc

View full text Add to dashboard Cite

Directed lithiation of substituted aromatics and heterocycles containing a directing metalating group with alkyllithium in anhydrous tetrahydrofuran or diethyl ether at low temperature provides the corresponding lithium intermediates. Reaction of the lithium reagents obtained in situ with various electrophiles gives the corresponding substituted derivatives in high yields. The process has been applied for various derivatives and has proven to be a convenient method for modification of ring systems. This brief review highlights the importance of directing metalating groups in directed lithiation of simple aromatic compounds and some common heterocycles as a tool for regioselective substitution.

show abstract