Ullmann‐Reaktionen an ortho‐(Acylamino)halogenaromaten

Abstract

ortho-(Acy1amino)halogenarornaten 1 und 3 kiinnen ohne Aktivierung durch Elektronenakzeptor-Substituenten mit metallischem Kupfer unter milden Bedingungen in guten Ausbeuten zu symmetrischen Biarylverbindungen 2 und 4 kondensiert werden. Grundsatzlich ist auch die Synthese unsymmetrischer Biarylverbindungen moglich. Vermutlich greift die Acylaminogruppe direkt unter Bildung einer intermediaren organischen Kupferverbindung in den Reaktionsablauf ein. Ullmann Reactions of ortho-(Acylamino)halogenoarenes * *)orrho-(Acy1amino)halogenoarenes 1 and 3 are condensed in presence of metallic copper under mild conditions to give symmetrical biaryl compounds 2 and 4 in good yields. In principle the synthesis of unsymmetrical biaryl compounds is also possible. The acylamino group probably participates directly by forming an organic copper intermediate.Die Ullmann-Reaktion I), d. h. die Synthese von Biarylderivaten durch Kondensation aromatischer Halogenverbindungen mit metallischen Agentien, vor allem Kupferpulver, gehort zum klassischen Kepertoire der organischen ,,Namen-Reaktionen" : Ar-Hal + Ar'-Hal -cu2Ha,z +2cu -+ Ar-Ar'

Direct Anodic Dehydrogenative Cross‐ and Homo‐Coupling of Formanilides

“…Despite the wide interest in such structural features, synthesizing 2,2′‐diformamidobiphenyls and 2,2′‐diaminobiaryls in general, is still a challenging task since anilines severely suffer from oxidative polymerization to polyaniline, also known as aniline black . A commonly used classical approach to symmetrical 2,2′‐diaminobiaryls is the copper‐mediated Ullmann reaction, whereas direct oxidative cross‐coupling reactions using stoichiometric amounts of Cu II salts have only been reported for a few naphthylamines and provided the desired biaryls in fairly low yield . An organocatalytic approach uses sigmatropic rearrangements of diaryl hydrazines in the presence of catalytic amounts of an acid to provide symmetrical 2,2′‐diaminobiaryls in good yield.…”

Bi-Blatter diradicals: convenient access to regioisomers with tunable electronic and magnetic properties

“…The requisite symmetric bi-benzo[ e ][1,2,4]triazines 3[6,6] and 3[7,7] were obtained starting from fluoroiodonitrobenzenes 4a and 4b , respectively, as shown in Scheme 2. Thus, the Ullmann coupling 68 of 4 in DMSO 69 gave the corresponding biphenyls 5[ m , n ] in moderate yields up to 49%. The same reaction conducted in dried DMF or DMA gave significant amounts of by-products containing the NMe 2 group.…”

One-pot synthesis of 1,4-dihydro-3,1-benzoxazine-2-thiones by the reaction of 2-lithiophenyl isothiocyanates with aldehydes or ketones

“…N- formamide. This compound was prepared in 87% yield by the standard N-formylation of 2-bromo-4-chlorobenzeneamine with formic acid in toluene under azeotropic conditions; 3 a pale-yellow solid; mp 147 C (hexane/THF) (lit., 6 3.3. Typical procedure for the preparation of 1,4-dihydro-3,1-benzoxazine-2-thiones 5 and 6…”