The Influence of Boronate Groups on the Selectivity of the Br–Li Exchange in Model Dibromoaryl Boronates

Krzysztof Durka , Sergiusz Luliński , Jaromir Smętek , Marek Dąbrowski , Janusz Serwatowski , Krzysztof Woźniak

Abstract

The selectivity of the Br/Li exchange reaction of 6-butyl-2-(2,5-dibromophenyl)-1,3,6,2-dioxazaborocane (2,5-Br2C6H3B(OCH2CH2)2NBu) and the analogous anionic derivatives, 2,5-Br2C6H3B(OiPr)3Li and 2,5-Br2C6H3BF3K, was investigated using nBuLi as the lithiating reagent. In the case of the former compound there was a slight preference for lithiation at the 5-position. For 2,5-Br2C6H3B(OiPr)3Li, the lithiation occured exclusively at C5, but for 2,5-Br2C6H3BF3K, 2-lithiation was preferred. Calculations performed for the lithiation of ortho- and meta-brominated phenyl boronates revealed that ortho-lithiated aryl boronates are thermodynamically more stable, but that the Br/Li exchange is generally dictated by kinetics, which accounts for the variation of selectivity depending on the type of boronate group. In addition, the successful generation of the 2,5-dilithiophenyl boronate species 2,5-Li2C6H3B(OCH2CH2)2NBu by a double Br/Li interconversion is reported. The Br/Li exchange in the related 6-butyl-2-[3-(2,5-dibromothienyl)]-1,3,6,2-dioxazaborocane, 2,5-Br2-3-ThB(OCH2CH2)2NBu, occured preferentially at the 5-position, but the product was readily transformed into the more stable 2-lithiated isomer. The use of 2 equiv. of nBuLi resulted in the efficient formation of the dilithiated species, 2,5-Li2-3-ThB(OCH2CH2)2NBu. The obtained lithiated aryl boronates were converted into functionalized arylboronic acids by treatment with selected electrophiles.
Author Krzysztof Durka (FC / DPC)
Krzysztof Durka,,
- Department Of Physical Chemistry
, Sergiusz Luliński (FC / DPC)
Sergiusz Luliński,,
- Department Of Physical Chemistry
, Jaromir Smętek (FC / DPC)
Jaromir Smętek,,
- Department Of Physical Chemistry
, Marek Dąbrowski (FC / DPC)
Marek Dąbrowski,,
- Department Of Physical Chemistry
, Janusz Serwatowski (FC / DPC)
Janusz Serwatowski,,
- Department Of Physical Chemistry
, Krzysztof Woźniak - [University of Warsaw (UW)]
Krzysztof Woźniak,,
-
- Uniwersytet Warszawski
Journal seriesEuropean Journal of Organic Chemistry, ISSN 1434-193X, [1099-0690]
Issue year2013
Vol2013
No15
Pages3023-3032
Publication size in sheets0.5
Keywords in EnglishLithiation, Boron, Metalation, Regioselectivity, Density functional calculations
ASJC Classification1605 Organic Chemistry; 1606 Physical and Theoretical Chemistry
DOIDOI:10.1002/ejoc.201300145
URL http://onlinelibrary.wiley.com/doi/10.1002/ejoc.201300145/abstract
ProjectBimetallic compounds derived from heteroarylboranes – new attractive building blocks for organic synthesis and material chemistry. Project leader: Luliński Sergiusz, , start date 29-08-2012, planned end date 28-08-2015, 505G/1020/0066000, Implemented
WCh Projects financed by NSC [Projekty finansowane przez NCN]
Languageen angielski
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Durka_et_al-2013-European_Journal_of_Organic_Chemistry.pdf 918.78 KB
Score (nominal)35
Score sourcejournalList
ScoreMinisterial score = 35.0, 04-02-2020, ArticleFromJournal
Ministerial score (2013-2016) = 35.0, 04-02-2020, ArticleFromJournal
Publication indicators Scopus Citations = 7; WoS Citations = 7; Scopus SNIP (Source Normalised Impact per Paper): 2013 = 0.834; WoS Impact Factor: 2013 = 3.154 (2) - 2013=3.001 (5)
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