Imines cross-coupling

Miller and co-workers have reported the use of thiazolylalanine-derived catalyst 65 to render the aldehyde-imine cross-coupling enantioselective [56]. The authors comment on the time sensitivity of this transformation and found that racemization occurs when the reaction goes to complete conversion. Electron-deficient aldehydes are the most efficient couphng partners for various tosylamides leading to the corresponding products 66, 68, and 69 (Scheme 8). 

Scheme 8 Miller and co-workers aldehyde imine cross-coupling catalyzed by thiazolylalanine-derived catalysts...

Mennen MS, Gipson JD, Kim YR, Miller SJ (2005a) Thiazolylalanine-derived catalysts for enantioselective intermolecular aldehyde-imine cross-couplings. J Am Chem Soc 127 1654... 

The thiazolium-catalyzed addition of an aldehyde-derived acyl anion with a Michael acceptor (Stetter reaction) is a well-known synthetic tool leading to the synthesis of highly funtionalized products. Recent developments in this area include the thiazolylalanine-derived catalyst 191 for asymmetric intramolecular Stetter reaction of a,P-unsaturated esters <05CC195>. However, these cyclizations proceed only in moderate enantioselectivities and yields even under optimized conditions. Thiazolium salt 191 has been used successfully for enantioselective intermolecular aldehyde-imine cross coupling reactions <05JA1654>. Treatment of tosylamides 194 with aryl aldehydes in the presence of 15 mol% of 191 and 2... 

TMSCl is essential as a promoter in a low-valent vanadium-catalysed reductive cyclotrimerization of aliphatic aldehydes, producing 1,3-dioxolanes (equation 4). It is also an essential component in the zinc-induced intramolecular imine cross coupling of diarylidene sulphamides subsequent cleavage provides a route to unsymmetiical l,2-diaryl-l,2-diaminoethanes (equation 5). It acts as an activating agent in the samarium-promoted cyclopropanation of allylic and a-allenic alcohols. 

A useful method for the preparation of functionalised thiazoles has been described. Palladium catalysed cross coupling reactions between 4-thiazolyl-5-acetyl triflates 36 and alkynes afforded 4-alkynyl-5-acetylthiazoles 37 in good yields (56-82%). If 37 is then treated with ammonia in methanol, thiazolo[5,4-c]pyridines 39 are formed, probably via the intermediate imine 38 which then undergos a regioselective 6-endo dig cyclisation <99EJOC3117>. 

Cross-Coupling Reactions between Carbonyl Compounds and Imine Derivatives... 

Unsymmetrical 1,2-diarylethane diamines, the formal cross-coupling products of two different imines, are produced by intramolecular reactions of dibenzylidene sulfamides with a combination of zinc and Me3SiCl in DME or Sml2 in THF (Equation (57)). 

Unsymmetrical vicinal diamines are prepared by reductive cross-coupling between nitrones and jY-/-butylsulfmyl imines with Sml2. The coupling proceeds in a high diastereoselective manner. Thus, optically pure unsymmetrical vicinal diamines are produced by using enantiomerically pure sulfinyl imines (Equation (74)). ... 

Recently, Olsson and coworkers have reported a cross-coupling reaction between seven-membered cyclic imidoyl chlorides and alkyl Grignard reagents (Scheme 36). The corresponding substimted imines, which are very difficult to prepare otherwise, are synthesized in good to excellent yields. 

Despite its apparent noble character, gold catalysts have been recently found to be active in many homogeneous and heterogeneous catalytic processes such as oxidation reactions, nucleophilic additions, cross-coupling reactions, and alkene and imine hydrogenations (69—71). Corma and co-workers showed that Au... 

It is known that electrochemical reduction of oximes in protic media occurs in two steps the N—O bond is first reduced to form an imine and the latter is then reduced to afford a primary amine1,29. Tallec has shown that the amine from oxime 33 can be trapped intramolecularly (equation 16)35. Interestingly, the SS diastereomer predominates the chiral pyrrolidine ring derivative serves to control the stereochemistry of formation of the new benzylic chiral center. Electrochemical reductive cross-coupling of O-methyl oximes with carbonyl compounds in isopropanol at a tin cathode affords adducts (equation 17) which can be reduced further to 2-amino alcohols36. In this fashion, menthone could... 

Cross-coupling reactions 5-alkenylboron boron compounds, 9, 208 with alkenylpalladium(II) complexes, 8, 280 5-alkylboron boron, 9, 206 in alkyne C-H activations, 10, 157 5-alkynylboron compounds, 9, 212 5-allylboron compounds, 9, 212 allystannanes, 3, 840 for aryl and alkenyl ethers via copper catalysts, 10, 650 via palladium catalysts, 10, 654 5-arylboron boron compounds, 9, 208 with bis(alkoxide)titanium alkyne complexes, 4, 276 carbonyls and imines, 11, 66 in catalytic C-F activation, 1, 737, 1, 748 for C-C bond formation Cadiot-Chodkiewicz reaction, 11, 19 Hiyama reaction, 11, 23 Kumada-Tamao-Corriu reaction, 11, 20 via Migita-Kosugi-Stille reaction, 11, 12 Negishi coupling, 11, 27 overview, 11, 1-37 via Suzuki-Miyaura reaction, 11, 2 terminal alkyne reactions, 11, 15 for C-H activation, 10, 116-117 for C-N bonds via amination, 10, 706 diborons, 9, 167... 

In addition, the cross-coupling of imines with allyl alcohols to generate Man-nich-type reaction products proceeded efficiently under similar conditions in methanol and ionic liquid ([ l- -butyl-3-methlyimidazolium] PFg) [19, 20] (Eq.9). 

Lithiation of compound 560 with s-BuLi-TMEDA in THF at —78 °C following an inverse addition protocol provided the anion 561. It reacts with primary alkyl iodides and triflates, silyl chlorides, diphenyl disulfide, epoxides, aldehydes, ketones, imines, acyl chlorides, isocyanates and sulfonyl fluorides to yield the expected compounds 562 (Scheme 152). The transmetallation of compound 561 with ZnBr2 allowed the palladium-catalyzed cross-coupling reaction with aryl and vinyl bromides837. When the reaction was quenched with 1,2-dibromotetrafluoroethane, the corresponding bromide 562 (X = Br) is obtained838. 

Several groups have utilized benzophenone imine as an ammonia equivalent in the palladium-catalyzed cross coupling. For example, Mullen and co-workers prepared a new thermotropic dye via the BINAP/Pd-coupling of the corresponding bromide, Eq. (130) [110]. Similarly, Basu reported the amination of a mixture of bromopyrene derivatives [111]. 

Cross-coupling between allylic alcohol and aldehyde is efficiently catalyzed by RuCl2(PPh3)3 in water to form an aldol-type product 48 [22], This reaction has limitations in the substituents of the aldehydes, and the use of aliphatic aldehydes provides complicated mixtures. Cross-coupling of imines with allylic alcohols under similar conditions generates Mannich-type reaction products 50 as major products, together with aldol-type products 48 [22], The selectivity of the reaction was improved by using methanol as the solvent, whereupon no aldol-type product was observed (Eqs. 12.19 and 12.20). 

N-Arylated 1,3-propanesultams 236 (R =Ar, R = H) are efficiently prepared from a Pd-catalyzed cross-coupling reaction with different aryl bromides in the presence of Xantphos <2004TL3305>. N-Fluorinated (-l-)-camphorsultams 237 (X = H, Cl, OMe R = F) have been prepared the corresponding imine 16 and difluoro derivative 238 were formed as by-products. The use of 237 is reported in Section 4.05.12.1 <1998JOC9604>. The syntheses of Ar-(l-alkynyl)-Oppolzer s sultams are reported in Section 4.05.6.3.4. Many examples of acylated Oppolzer s sultams are reported in Section 4.05.12.1. 

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