A Route to Regioselectively Functionalized Carbazoles, Dibenzofurans, and Dibenzothiophenes Through Anionic Cyclization of Benzyne‐Tethered Aryllithiums.
“…In 2006, Fananas group [7] found that the treatment of 2-fluorophenyl 2-iodophenyl thioether with 3.3 equiv. of t-BuLi, which further reacted with selected electrophiles, gave rise to functionalized dibenzothiophene derivatives (Scheme 1).…”
Section: C-x Cleavage For Dibenzothiophenes Synthesismentioning
“…In 2006, Fananas group [7] found that the treatment of 2-fluorophenyl 2-iodophenyl thioether with 3.3 equiv. of t-BuLi, which further reacted with selected electrophiles, gave rise to functionalized dibenzothiophene derivatives (Scheme 1).…”
Section: C-x Cleavage For Dibenzothiophenes Synthesismentioning
“…The most commonly used route to 1functionalized dibenzothiophenes is based on an elegant intramolecular anionic cyclization developed by Sanz and co-workers (Equation 1, Scheme 1). 8 Thiophenol 1a is converted to benzyne precursor 2a which undergoes an intramolecular anionic cyclization to 1-lithiodibenzothiophene 3a-Li, which can be quenched with electrophiles. Pummerer-based approaches beginning with cross-coupling of 4a to form biaryl 4b, which can undergo oxidative conversion to 1-functionalized dibenzothiophene 3b (Equation 2, Scheme 1).…”
Section: Scheme 1 Representative Syntheses Of 1-substituted Dibenzotmentioning
confidence: 99%
“…Spectral data agreed with literature values. 8 1 H NMR (500 MHz, CDCl3): δ 7.90 (dd, J= 7.9, 1.4 Hz, 1H), 7.34-7.31 (m, 1H), 7.13 (dd, J= 7.9, 1.5, 1H), 7.06-6.98 (m, 2H), 6.93-6.84 (m, 3H), 3.24 (s, 3H). 13…”
<p>The 1-substituted dibenzothiophene motif is an unusual substitution pattern. We demonstrate a simple one-pot preparation of 1-lithiodibenzothiophene via a cascade of two benzyne additions and conversion to the aldehyde, boronic ester, and iodide. This work avoids the use of precious metals or tert-butyllithium and is shorter than existing routes to these compounds. We also report an improved route to the isomeric 3-substituted naphthothiophene scaffold. These protocols will allow rapid access to families of these two related heteroacenes.</p>
“…In the fragmentation of their molecular ions using atmospheric pressure chemical ionization (APCI) tandem mass spectrometry (MS/MS) in positive ion mode, the positively charged biradicals of diphenyl sulfides were generated by elimination of iodine radicals. Although considerable efforts have been dedicated to investigating the fragmentation of various sulfur‐containing compounds, the dissociation of the positively charged biradicals of diphenyl sulfides has not been systematically discussed.…”
RATIONALE: Aryl thioethers are potentially useful precursors for constructing various biologically active sulfurcontaining heterocycles. The detailed relationship between the losses of HS radical and CS with the spin multiplicity of positively charged diphenyl sulfide biradicals derived from 3-iodophenyl phenyl sulfides has not been obtained by tandem mass spectrometry combined with theoretical calculations. METHODS: Collision-induced dissociation mass spectrometry experiments were carried out using an ion trap mass spectrometer with APCI in positive mode. The MS/MS experiment for dibenzothiophene was performed by CI triple-quadrupole mass spectrometry in positive ion mode. The accurate masses of fragments were obtained by reflective TOFMS with an EI source. Theoretical calculations were achieved by the density functional theory method at the B3LYP level with the 6À31+G(d, p) basis set in the Gaussian 03 package of programs. RESULTS: In the fragmentation of positively charged diphenyl sulfide biradicals, losses of HS· and CS were observed, which were proposed to originate from spin multiplicity transformation from a triplet ground state to a singlet excited state and a phenyl radical shift in triplet ground state, respectively. Moreover, a protonated dibenzothiophene intermediate was confirmed to exist in the process of HS radical loss. A linear correlation was established between the product ion abundance from the two competitive losses and the Hammett constants (σ) of substituent groups on the benzene ring. CONCLUSIONS: The eliminations of HS· and CS in the fragmentation of positively charged diphenyl sulfide biradicals were triggered by spin multiplicity transformation from a triplet ground state to a singlet excited state and a phenyl radical shift in a triplet ground state, respectively. Based on theoretical calculations, two competitive neutral losses are thermodynamically controlled.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.