Cross-coupling synthesis

Asymmetric cross-coupling Synthesis of natural products... 

DoM-Ullmann Cross-Coupling. Synthesis ofAr-X-Ar (X = 0, N, S) under Modified Ullmann Reaction Conditions (General Procedure, Table 14.19)... 

DoM - Suzuki-Miyaura cross-coupling synthesis of amphimedine, see Guillier, F., Nivoliers, F., Godard, A., Marsais,... 

The thioboration of terminal alkynes with 9-(alkylthio)-9-borabicyclo[3.3.1]-nonanes (9-RS-9-BBN) proceeds regio- and stereoselectively by catalysis of Pd(Ph,P)4 to produce the 9-[(Z)-2-(alkylthio)-l-alkeny)]-9-BBN derivative 667 in high yields. The protonation of the product 667 with MeOH affords the Markownikov adduct 668 of thiol to 1-alkyne. One-pot synthesis of alkenyl sulfide derivatives 669 via the Pd-catalyzed thioboration-cross-coupling sequence is also possible. Another preparative method for alkenyl sulfides is the Pd-catalyzed cross-coupling of 9-alkyl-9-BBN with l-bromo-l-phe-nylthioethene or 2-bromo-l-phenylthio-l-alkene[534]. 

Organoboranes are reactive compounds for cross-coupling[277]. The synthesis of humulene (83) by the intramolecular cross-coupling of allylic bromide with alkenylborane is an example[278]. The reaction of vinyiborane with vinyl-oxirane (425) affords the homoallylic alcohol 426 by 1,2-addition as main products and the allylic alcohol 427 by 1,4-addition as a minor product[279]. Two phenyl groups in sodium tetraphenylborate (428) are used for the coupling with allylic acetate[280] or allyl chloride[33,28l]. 

The von Richter cinnoline process was further extended to solid-phase synthesis. The route began from benzylaminomethyl polystyrene and the required diverse o-haloaryl resins represented by 21 were prepared from substituted o-haloanilines. A Pd-mediated cross-coupling reaction with 21 and the alkynes provided the alkynylaryl derivatives represented by alkyne 22. The von Richter cyclization reaction with hydrobromic or hydrochloric acid in acetone/HaO and cleavage from the resin occurred in the same step to furnish the cinnoline derivatives 23 in 47-95% yield and 60-90% purity (no yield reported for each entry). 

Catalytic cross-coupling reactions in synthesis of bihetarenes and arylhetarenes 98T263. 

The first total synthesis of 87 was published in 1990 (90TL1523). 5-Hydroxyindole (88) was mesylated and then reduced with sodium cyanoborohydride to give an indoline which was brominated to afford the bromoindoline 89 in good yield (Scheme 33). Cross-coupling with ortho-formyl boronic acid under Suzuki conditions, followed by air oxidation of the resulting cyclized product, followed by reduction of the lactam formed with excess Red-Al gave the target compound 87. 

In summary, palladium-mediated reactions, especially cross-coupling reactions have found many applications in quinoline synthesis. It is noteworthy that due to the a and S activation for the C(2) and C(4) positions, even 2-chloro- and 4-chloro-quinolines are viable substrates for palladium-catalyzed reactions under standard conditions. With the advent of the palladium chemistry and more commercially available organometallic substrates, more palladium-mediated quinoline syntheses are to be added to the repertoire of quinoline chemistry. 

One of the first examples was the above mentioned work from Yoshino et al. [7] concerning the synthesis of poly(9,9-dialkylfluorene)s via oxidative coupling of fluorene derivatives. Poly(9,9-dialkylfluorene) derivatives have been also synthesized via Ni- and Pd-catalyzed aryl-aryl homo- and cross-coupling reactions of sui-... 

The authors used a synthesis of 9,9-spirobitluorenes 32 which was developed by Clarksen and Gomberg [60] and which includes the addition of biphenyl-2-yl-magnesium iodide to fluorenone and subsequent cyclization with protic acids. To obtain 2,2,, 7,7 -arylated 9,9-spirobifluorenes 33, 9,9-spirobifluorene (32) was tetrabrominated [58] to yield 34 followed by a Suzuki-type aryl-aryl cross-coupling with various oligoaryl and oligoheteroaryl boronic acids to obtain the 2,2, 7,7 -tetraarylated derivatives 33. 

The utility of the Suzuki reaction in the challenging arena of natural product total synthesis has been explored. The constitution of bombykol (106) (see Scheme 26), a well-known pheromone, lends itself to a Suzuki coupling. Indeed, in a short stereospecific synthesis of 106, Suginome et al. demonstrated that ( )-vinylboronic acid ( )-104 can be smoothly cross-coupled with (Z)-l-pentenyl bromide [(Z)-105] 44 the configurations of both coupling partners are preserved in the C-C bond forming process. 

The late Professor J. K. Stille pioneered the development of a very effective and versatile palladium-mediated C-C bond forming method - the palladium-catalyzed cross-coupling of organic electrophiles with organostannanes.48 This process continues to enjoy much success in organic synthesis because it proceeds in high yields under mild reaction conditions and because it tolerates a... 

The key step in a short and efficient synthesis of pleraplysillin-1 (127) is the palladium-catalyzed cross-coupling of vinylstannane 125 with vinyl triflate 126 (see Scheme 33). This synthesis is noteworthy in two respects. First, vinyl triflate 126 is generated regio-specifically from the kinetic enolate arising from a conjugate reduction of enone 124 the conjugate reduction of an enone is, in fact, a... 

An intramolecular palladium(o)-catalyzed cross-coupling of an aryl iodide with a trans vinylstannane is the penultimate maneuver in the Stille-Hegedus total synthesis of (S)-zearalenone (142) (see Scheme 38).59 In the event, exposure of compound 140 to Pd(PPh3)4 catalyst on a 20% cross-linked polystyrene support in refluxing toluene brings about the desired macrocyclization, affording the 14-membered macrolide 141 in 54% yield. Acid-induced hydrolysis of the two methoxyethoxymethyl (MEM) ethers completes the total synthesis of 142. 

Nakamura, H., et al. (2000). Convergent and short-step synthesis of dl-Cypridina luciferin and its analogues based on Pd-mediated cross coupling. Tetrahedron Lett. 41 2185-2188. 

Scheme 16 Construction of a nine-membered cyclic ether with a (Z,Z)-1,3-diene unit by sequential RCM and silicon-assisted intramolecular cross coupling in Denmark s synthesis of brasilenyne (85) [65]...

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