Ullmann coupling reactions

In a synthesis of decinine, a phenol was protected as a methanesulfonate that was stable during an Ullmann coupling reaction and during condensation, catalyzed by calcium hydroxide, of an amine with an aldehyde. Aryl methanesulfonates are cleaved by warm sodium hydroxide solution. 

In general, imines are too reactive to be used to protect carbonyl groups. In a synthesis of juncusol, however, a bromo- and an iodocyclobexylbnine of two identical aromatic aldehydes were coupled by an Ullmann coupling reaction modified by Ziegler. The imines were cleaved by acidic hydrolysis (aq. oxalic acid, THE, 20°, 1 h, 95% yield). Imines of aromatic aldehydes have also been prepared to protect the aldehyde during ring metalation with. -BuLi. ... 

Meyers has also reported the use of chiral oxazolines in asymmetric copper-catalyzed Ullmann coupling reactions. For example, treatment of bromooxazoline 50 with activated copper powder in refluxing DMF afforded binaphthyl oxazoline 51 as a 93 7 mixture of atropisomers diastereomerically pure material was obtained in 57% yield after a single recrystallization. Reductive cleavage of the oxazoline groups as described above afforded diol 52 in 88% yield. This methodology has also been applied to the synthesis of biaryl derivatives. 

We investigated the catalytic performance of the CU2O coated copper nanoparticles for Ullmann coupling reactions. When the coupling reactions using aryl bromides such as 2-... 

Picryl chloride has been used successfully in a number of copper-mediated Ullmann coupling reactions. 2,2, 4,4, 6,6 -Hexanitrobiphenyl has been synthesized by heating picryl chloride with copper powder. The same reaction in the presence of a hydride source (hot aqueous alcohol) yields 1,3,5-trinitrobenzene (TNB). The Ullmann reactions between picryl chloride and isomeric iodonitrobenzenes with copper bronze in DMF has been used to synthesize 2,2, 4,6-, 2,3, 4,6-, and 2,4,4, 6-tetranitrobiphenyls. ... 

Discussions of oxazolines as chiral directing groups are included in the previous sections under the appropriate reaction classifications. Meyers has already published a recent review of chiral oxazolines (1998) that focused primarily on their use in aromatic reactions and Ullmann coupling reactions in particular. The examples of oxazolines as chiral directing groups described in this section will include reactions that are not discussed in any previous section of this chapter. 

TABLE 8.30 DIASTEREOSELECTIVITY IN ULLMANN COUPLING REACTIONS (SCHEME 8.158), 466... 

It was reasoned that if ferrocene behaved as an aromatic system, haloferro-cenes should undergo the Ullmann coupling reaction. Biferrocenyl (XXXVIII) was obtained from this reaction and was shown to be identical in every respect with the anomalous material isolated previously (82, 84). Somewhat surprisingly, it was found that the reaction of iodoferrocene and copper produces XXXVIII in practically quantitative yield, even at temperatures as low as 60°. 

It is conceivable that Ullmann coupling reactions of iodothiophenes in presence of copper might involve thienylcopper intermediates. Intramolecular versions of this proceed in excellent yield. For instance, nearly quantitative yields of the tricyclic compound (502) by this process has been reported (70JCS(C)273). 

Thiophene, 2-hydroxy-5-methyl-synthesis, 4, 926 Thiophene, iodo-Grignard reagents, 4, 79, 831 photolysis, 4, 832 reactions, 4, 932 with phenyllithium, 4, 831 synthesis, 4, 835, 934 Ullmann coupling reactions, 4, 837 Thiophene, 2-isopropyl-3-methyl-synthesis, 4, 901 Thiophene, mercapto-reactions, 4, 78 stability, 4, 825 synthesis, 4, 80, 835, 930-931 tautomerism, 4, 38, 727 Thiophene, 2-mercapto-5-methylthio-synthesis, 4, 872 Thiophene, 2-methoxy-chloromethylation, 4, 759 Thiophene, 3-methoxy-chloromethylation, 4, 759 Thiophene, 5-methoxy-2,4-dinitro-Meisenheimer complexes, 4, 815 Thiophene, 2-methoxy-5-methyl-Vilsmeier formylation, 4, 759-760 Thiophene, 2-methoxy-3-nitro-reactions, 4, 827 Thiophene, 2-methyl-bromination, 4, 799-800 conformation, 4, 32 HNMR, 4, 730 metallation, 4, 773 synthesis, 4, 885, 887 trifluoroacetylation, 4, 751 Thiophene, 3-methyl-bromination, 4, 799-800 conformation, 4, 32 H NMR, 4, 730 metallation, 4, 60 oxidation, 4, 800... 

The enantiomerically pure bridged biphenyl, (—)-(R)-3,9-bis[4-(dodecyloxy)benzoyloxy]-5,7-dihydro-l,ll-dimethyl-dibenzo[c,( ]thiepine 80, was prepared from enantiomerically pure diiodide 197 (Scheme 25) <1998JOC3895>. The synthesis of the precursor 197 was based on Ullmann coupling reaction of the chiral oxazoline (-)-(S)-195. 

An organocopper intermediate was detected by Lewin and Cohen in the reaction of / -iodotoluene with copper in a good complexing solvent (184). Analysis of protonated aliquots from a reaction performed in quinoline indicated an accumulation of />-tolylcopper to a maximum of 43% after 95 hours, at which point the iodide was consumed, and then a slow decrease to by dimerization. Other experiments also indicate the formation of an arylcopper compound in Ullmann reactions (127,141, 210). The isolation of deuterated products, presumably from the decomposition of an intermediate organocopper species in deuterated benzene and cyclohexane, suggested decomposition to free radicals (127). Decompositions of certain o-haloarylcopper intermediates by a benzyne mechanism cannot be totally excluded. The formation of a dichlorobenzene and by-products such as dibenzofuran and triphenylene from only the ortho isomer of the chloroiodobenzenes in Ullmann coupling reactions (210)... 

Ullmann coupling reactions of perfluoroaryl ttnd -heteioaiyl iodides and bromides with copper proceed readily. ... 

Ullmann Coupling Reaction. Axially dissymmetric biaryls have been synthesized via an intramolecular Ullmann coupling reaction of BINOL-derived aryl diesters (eq 6). In the example shown, the functionalized binaphthyl is obtained with high ee after hydrolysis of the intermediate 12-membered cyclic diester. 

Barbier-Wieland degradation Boudroux-Chichibabin synthesis Bouveault aldehyde synthesis Darzens synthesis Friedel-Crafts Reaction Gatterman-Koch reaction Grignard reaction Reformatsky reaction Saytzeff reaction Ullmann coupling reaction Wiirtz coupling reaction Wiirtz-Fittig reaction... 

Ma, D., Cai, Q. N,N-Dimethyl Glycine-Promoted Ullmann Coupling Reaction of Phenols and Aryl Halides. Org. Lett. 2003, 5, 3799-3802. 

LIndley, J., Lorlmer, J. P., Mason, T. J. Enhancement of an Ullmann coupling reaction Induced by ultrasound. Ultrasonics 1986, 24, 292-293. 

In a synthesis of decinine, a phenol was protected as a methanesulfonate that was stable during an Ullmann coupling reaction and during a condensation, catalyzed by calcium hydroxide, of an amine with an aldehyde. Aryl methanesulfonates are cleaved by warm sodium hydroxide solution, with LDA (THF, -78°C to rt, 57-95% yield) or with TMSOK/CH3CN. An aryl methanesulfonate was cleaved to a phenol by phenyllithium or phenylmagnesium bromide it was reduced to an aromatic hydrocarbon by sodium in liquid ammonia. ... 

Coupling reactions. Various (Heck, Stille, Suzuki, Sonogashira, and Ullmann) coupling reactions are mediated by a stable palladacycle 1. ... 

Ullmann coupling reactions of iodothiophenes were referred to in CHEC-I <84CHEC-I(4)741>. This procedure has been made use of in the synthesis of cyclobuta [1,2-c 3,4-c ]dithiophene <85CC880>. The first step in the synthesis is the Cornforth modification of the Ullmann procedure (MeCN, Me2CO, aq. NH3, Cu, CUSO4 25 °C) (Equation (58)). The Ullmann reaction has also been used for the synthesis of several substituted phenylthiophene derivatives <85JHC1667>. 

Scheme 5.8. Preparation of Biaryls by the Ullmann Coupling Reaction...

The substituents in the phenyl (aryl) ring have a remarkable influence on the reactivity of the aryl halide in the Ullmann coupling reaction [4,5,9,10]. They can be divided into three groups ... 

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