Halogen–lithium exchange versus deprotonation: regioselective mono- and dilithiation of aryl benzyl sulfides. A simple approach to α,2-dilithiotoluene equivalents

Kliś, Tomasz; Serwatowski, Janusz; Wesela‐Bauman, Grzegorz; Zadrozna, Magdalena

doi:10.1016/j.tetlet.2010.01.074

Cited by 10 publications

(5 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…We isolated the methylated boronic acid 2a in the good yield. As we demonstrated in our previous work, lithiation of 6 should be carried out in Et 2 O in order to stabilize the ortho ‐lithiated 6‐Li 15. However, the use of diethyl ether results in very slow deprotonation in the benzylic position and we isolated only traces of 3a .…”

Section: Resultsmentioning

confidence: 69%

Efficient and rapid exact gene replacement without selection

Cross¹,

Pecani²

2010

Yeast

View full text Add to dashboard Cite

We describe a highly efficient method for exact gene replacement in budding yeast. Induction of rapid and efficient recombination in an entire cell population results in at least 50% of the recombinants undergoing a specific switch of the endogenous copy to a specific mutated allele, with no remaining markers or remnant of foreign DNA, without selection. To accomplish this, a partial copy of the replacement allele, followed by an HO cut site, is installed adjacent to the wild-type locus, in a GAL-HO MATa-inc background. HO induction results in near-quantitative site cleavage and recombination/gene conversion, resulting in either regeneration of wild-type, or switch of the endogenous allele to the mutant, with accompanying deletion of intervening marker sequences, yielding an exact replacement. Eliminating the need for selection (over days) of rare recombinants removes concerns about second-site suppressor mutations, and also allows direct phenotypic analysis even of lethal gene replacements without the need of a method to make the lethality conditional, or to employ regulated promoters of unknown strength compared to the endogenous promoter. To test this method, we tried two known lethal gene replacements, substituting the non-essential CDH1 gene with a dominantly lethal version mutated for its Cdk phosphorylation sites, and substituting the essential CDC28 gene with two recessively lethal versions, one containing an early stop codon and another one inactivating Cdc28 kinase activity. We also tested a gene replacement of unknown phenotypic consequences: replacing the non-essential CLB3 B-type cyclin with a version lacking its destruction box.

show abstract

Section: Resultsmentioning

confidence: 69%

Efficient and rapid exact gene replacement without selection

Cross¹,

Pecani²

2010

Yeast

View full text Add to dashboard Cite

show abstract

“…As we demonstrated in our previous work, lithiation of 6 should be carried out in Et 2 O in order to stabilize the ortho-lithiated 6-Li. [15] However, the use of diethyl ether results in very slow deprotonation in the benzylic position and we isolated only traces of 3a. The slow lithiation of 4 and 5 is probably caused by the substituents carrying the negative charge.…”

Section: Methodsmentioning

confidence: 79%

Functionalization of some benzylthioarylboronic acids by benzylic lithiation of their N‐butyldiethanolamine esters or lithium (triisopropoxy)borates

Durka

Kliś

Serwatowski

et al. 2011

Applied Organom Chemis

Self Cite

View full text Add to dashboard Cite

The reaction of benzylthioarylboronic acids protected as N-butyldiethanolamine esters or as triisopropoxyborates with organolithium bases or lithium diisopropylamide (LDA) has been investigated. The benzylic lithiation occurs selectively using LDA at −68• C. The stability of the resultant borio-lithio intermediates is strongly influenced by the position of the boron atom in the phenyl ring. The reaction with various electrophiles affords new arylboronic acids substituted in the benzylic position.

show abstract

“…The five‐membered ring in 5 is not strained because of the presence of two sp 3 hybrydized carbon atoms. Although the crystal structure of many boronic acids like 4‐tolylboronic acid or its catechol ester have been already published,15–17 the number of crystal structures of aromatic organo‐oxyboranes containing sulfur atoms is limited to 2‐benzylthiophenylboronic acid which forms characteristic dimers through hydrogen bonds 18. However, the structures of 4‐methylthiophenyl‐bis‐mesitylborane19 and related sulfur‐containing triarylboranes were also recently published 20, 21…”

Section: Introductionmentioning

confidence: 99%