Tandem Synthesis of 9,10-Dihydro-9,10-diboraanthracenes via Elusive ortho-Lithiated Phenylboronates
Sergiusz Luliński , Jaromir Smętek , Krzysztof Durka , Janusz Serwatowski
AbstractA simple general protocol is reported for the synthesis of functionalised 9,10-dihydroxy-9,10-dihydro-9,10-diboraanthracenes by treatment of the appropriate substituted (2-halophenyl)boronates with tBuLi. The reaction apparently occurs through the formation of ortho-lithiated phenylboronates. These elusive species possess a trivalent Lewis-acidic boron atom in the vicinity of a strongly nucleophilic lithiated carbon atom. The results of DFT calculations indicate that Br/Li exchange is kinetically favored over nucleophilic alkylation of the boron atom, which contrasts with the behaviour of the sterically less hindered nBuLi. The results are consistent with lower yields of 9,10-dihydro-9,10-diboraanthracenes obtained by using the latter reagent. Subsequent steps of the cascade reaction sequence involve trapping of the reactive lithium/boron intermediate in situ with the starting boronate, followed by a second halogen/lithium exchange and final ring closure. Isolation of 9,10-dihydroxy-9,10-dihydro-9,10-diboraanthracenes was further aided by their complexation with 8-hydroxyquinoline.
|Journal series||European Journal of Organic Chemistry, ISSN 1434-193X, [1099-0690]|
|Publication size in sheets||0.5|
|Keywords in English||Heterocycles, Lithiation, Halogens, Borates, Density functional calculations|
|Project||Bimetallic 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
|Score|| = 35.0, 07-09-2020, ArticleFromJournal|
= 35.0, 07-09-2020, ArticleFromJournal
|Publication indicators||= 17; = 16; = 1.0; : 2013 = 0.834; : 2013 = 3.154 (2) - 2013=3.001 (5)|
|Citation count*||1 (2014-12-11)|
* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.