Iridium-catalyzed C–H coupling reaction of heteroaromatic compounds with bis(pinacolato)diboron: regioselective synthesis of heteroarylboronates

Abstract

Abstract-TheRegioselective synthesis of bis(boryl)heteroaromatics was also achieved by using an almost equimolar amount of substrates and the diboron.--

Iridium-catalyzed borylation of thiophenes: versatile, synthetic elaboration founded on selective C–H functionalization

“…26 Recognizing that this transformation's simplicity could offer advantages over traditional routes to arylboron compounds, we explored the generality of this reaction with arenes, including the first extensions to heterocyclic substrates. [27][28][29] Despite improvements in catalyst generation, 28,30 application of this methodology to substituted thiophenes is limited to five substrates: 2-methylthiophene, [31][32][33] 2-cyanothiophene, 32 2-bromothiophene, 32 2-methoxythiophene, 33 and 2-trifluoromethylthiophene. 33 These reactions yield 5-borylated products exclusively in accord with the preference for borylation of C-H bonds adjacent to formally sp 3 -hybridized heteroatoms in 5-membered heterocycles.…”

Totalsynthese von Nosiheptid

“…[36] Tristhiazolylpyridin 42, [37] (57), [36] 1,2-(Z)-Methoxycarbonyl-1,3-bis(trimethyl-silyloxy)-1,3-butadien (65), [37] 2-Nitro-6-(2'-tetrahydropyranyloxymethyl)phenyl-brenztrauben-säureethylester (75), [153] 3-Hydrox-ypyridin-5,6-bis(trideutero-methoxycarbonyl)-2-carbon-säuremethylester (97-d 6 ), [241] 131 3-Hydroxypicolinsäuremethylester (100), [278] L-Boc-Thr(TBS)-OH (140), [201] L-FmocThr(TBS)-OH (143), [202] 2'-Bromacetyl-pyridin (161), [219] 6-Brom-3-hydroxypicolinsäure-methyl-ester (204), [267] 4-(Tributyl-stannyl)-1-trityl-1H-imidazol (217), [269] 4,6-Dibrom-3-hydroxy-picolinsäure-diemethylester (228), [278] Dess-Martin-Periodinan, [312] 3-Hydroxypyridin-2,5,6-tricarbonsäure-trimethylester, [37] 3-Meth-oxypicolinsäuremethyl-ester(240) [308] Indol-2-boron-säurepinakolester, [313] Indol-3-boronsäurepinakol-ester, [314] 1H-Pyrrol-3-boronsäure-pinakolester, [315] 1-(Tetrahydro-2H-pyran-2-yl)-1H-pyrazol-5-boronsäurepinakol-ester, [268] Pyrazol-4-boronsäurepinakolester, [314] (R)-2-Azido-3-(tritylthio)-propansäureallyl-ester, [37] PyDOP. [225] Dichlormethan [316] die Sporen wurden anschließend geerntet und in Glycerol gelagert.…”

Recent progress in the synthesis of pyridinylboronic acids and esters

“…Two main types of ligand are reported in the literature for the synthesis of pyridinylboronic acids esters: bipyridine compounds (14a-d) and pyridinylimine compounds (15a, b). [67][68][69][70][71][72][73][74][75] 2.4.2. The regioselectivity of the iridium-or rhodium-catalyzed C-H bond borylation.…”

“…In general, the 2,6-disubstituted pyridine gave only 4-pyridinylboronic esters, while pyridine or monosubstituted pyridines gave a mixture of 3-and 4-pyridinylboronic esters. [73][74][75] The borylation selectivity with ligands 14b and 14d were observed to be different: borylation occurred in the position adjacent to the nitrogen atom in 14b ( R = tBu), but occurred at the 5-position (i.e. ortho to the methoxy groups) in 14d (R = OMe).…”