Switchable highly regioselective synthesis of 3,4-dihydroquinoxalin-2(1H)ones from o-phenylenediamines and aroylpyruvates

• Juraj Dobiaš,
• Marek Ondruš,
• Gabriela Addová and
• Andrej Boháč

Beilstein J. Org. Chem. 2017, 13, 1350–1360, doi:10.3762/bjoc.13.132

• , rt, 3 days), differing only by the additives p-TsOH or HOBt/DIC (hydroxybenzotriazole/N,N’-diisopropylcarbodiimide). Both selected methods are simple, general and highly regioselective (72–97%). A mechanism for the regioselectivity was also proposed and discussed. This study can be used as a guide

• could expand the synthetic impact of our results. Keywords: controlled regioselectivity; cyclocondensation; 3,4-dihydroquinoxaline-2(1H)one; HOBt/DIC; mechanism; Introduction The quinoxalin-2(1H)-one moiety is frequently found in compounds that exhibit biological activity, particularly antimicrobial

• partial formation of a stabilized enolate anion by DMAP deprotonation. Therefore, using DMAP activation is not recommended for EWG-substituted diamines. e) The reaction of activated ester 12d (obtained in situ after treatment of carboxylic acid 12b with HOBt/DIC, Scheme 6) and a diamine 11a–f (general

Sequence-specific RNA cleavage by PNA conjugates of the metal-free artificial ribonuclease tris(2-aminobenzimidazole)

• Friederike Danneberg,
• Alice Ghidini,
• Plamena Dogandzhiyski,
• Elisabeth Kalden,
• Roger Strömberg and
• Michael W. Göbel

Beilstein J. Org. Chem. 2015, 11, 493–498, doi:10.3762/bjoc.11.55

• : 45 bar H2, Pd/C (10%), MeOH sat. with NH3, 60 °C, 5 h, rt, overnight, 37%; f: Mukaiyama’s reagent, NEt3, DMF, 22 h, rt, 56%. Boc-ON: 2-(tert-butoxycarbonyloxyimino)-2-phenylacetonitrile. Synthesis of PNA conjugates. Conditions: a: 1) 9, HOBt, DIC, DMF, rt, 24 h; 2) piperidine, DMF, rt, 30 min; b: 1

• ) 8, HOBt, DIC, NEt3, DMF, rt, 72 h; 2) TFA/H2O/triisopropysilane (95:2.5:2.5), rt, 3 h. Supporting Information Supporting Information File 230: Experimental procedures and characterization data. Acknowledgements Financial support by the European 7th framework program (238679, PhosChemRec), the

Glycosylation efficiencies on different solid supports using a hydrogenolysis-labile linker

• Mayeul Collot,
• Steffen Eller,
• Markus Weishaupt and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 97–105, doi:10.3762/bjoc.9.13

• . CsOAc, TBAI, DMF, 60 °C; 3. p-TsOH·H2O, MeOH, DCM, rt; (b) 1. 1 and 18, 19, 20, 21 or 22, HOBt, DIC, DMF, rt; 2. Ac2O, pyridine, DCM, rt; 3. p-TsOH·H2O, MeOH, DCM, rt; (c) 1. 2 and 18, 19, 20 or 22, pyridine, DCM, rt; 2. Ac2O, pyridine, DCM, rt; 3. 1, Cs2CO3, DMF, TBAI, 60 °C; 4. CsOAc, TBAI, DMF, 60 °C