Domino coupling

When using this domino coupling, polycyclic compounds can also be obtained... 

Rhodium-catalyzed three-component domino coupling of 1,6-diyne 41, hydrosilane, and Cgo proceeds to give fullerene adduct 42 in good yield (Eq. 10) [29]. In this case, dienophile Cgo does not interfere with the silylcarbocyclization process and traps the 1,2-bis-exo-methylidenecyclopentane intermediates to furnish the corresponding Cgo-linked carbo- or heterocycle 42. 

Domino coupling reactions of aryl halides with norbornene and its derivatives provide a simple route to PAHs. In a four component sequence, norbornene (73) is arylated with an excess of iodobenzene to the terphenyl 74, that can be converted to the benz[e]pyrenes 75 and 76 by classical aromatic conversion reactions [131]. The domino sequence is a consequence of the fact that the five-membered intermediate palladacycle 77 a is able to add a second molecule of iodobenzene (77a —> 77b), and the intermediate arylpalladium halide resulting from reductive elimination in 77 b can even add a third molecule of iodobenzene before the final elimination of the Pd(0) complex PdL2 occurs (see Scheme 38). 

Similar sequential domino reactions occur using cyclic alkenes such as nor-bornene [101-105], indene [106], and dihydronaphthalene [107]. In these reactions, 3 1 coupling products can be formed. In the case of norbornene, up to 4 1 coupling is observed [104]. Notably, acyclic vinylsulfones specifically undergo 3 1 domino coupling (Eq. 38) [108]. 

Isomerization of the coupling products of 1-arylpropargyl alcohols with electron-deficient halides generate a,j6-unsaturated aryl ketones, which undergo further condensation to afford heterocycles such as pyrroles and pyrimidines [25], For example, domino coupling-isomerization-condensation reactions of 1-phenylpropargyl alcohol (1", 2-bromothiazole, and methylhydrazine generated the enone 18, and the pyrazoline 19 was obtained by the reaction of methylhydrazine [25],... 

The Sonogashira coupling of the terminal alkyne in 58 with the ditriflate 59 occurred selectively in the presence of Pd-Cul catalyst to give 60. Then domino coupling/Diels-Alder reaction of 60 occurred to afford 62 via 61 at room temperature. It is interesting that [4 + 2] cyclization of nonactivated diene and dienophile (a triple bond) occurred even at 20 °C, and the result suggests a possible role of the Pd catalyst. The compound 62 was spontaneously transformed completely to the final product 63 through oxidative aromatization [31]. 

A convenient base-mediated strategy to synthesize 3-aroyl-4-methyl-(or benzyl)-2-methylthio furans (tri-substituted furans) was developed through domino coupling/annulation between readily available a-oxo ketene dithioacetals and propargyl alcohols (140BC8947). 

De Meijere, A. and Erase, S. (1999) Palladium in action domino coupling and aUylic substitution reactions for the efficient construction of complex organic molecules. J. Organomet. Chem., 576, 88-110. 

Dyker, G. and Kellner, A. (1994) A palladium catalyzed domino coupling process to substituted phenanthrenes. Tetrahedron Lett., 35, 7633-6. 

Shinokubo and coworkers [79] performed a domino coupling reaction of aryl boronic acids 139 with internal alkynes 140 and acrylates 141 by using a rhodium catalyst in water to give nine examples of the 1,3-diene derivatives 142 in 37-81% yields (Scheme 12.55). The reaction indicates that the use of water offers the possibility to optimize known reactions, leading to novel transformations. 

Recently, a general Cu(I)-catalyzed version leading to 2-aryl and 2-heteroaryl indoles 267 was reported by Cacdii (Scheme 9.93) [190]. Thus, o-iodotrifluoroace-tanilides 265 and terminal alkynes 266 underwent the Cu(I)-catalyzed domino coupling-cycloisomerization reaction with a concomitant deprotection of the tri-fluoroacetyl group, providing NH-indoles 267. Moderate to excellent yields can be... 

Y. Yamamoto, H. Hayashi, T. Saigoku, H. Nishiyama, J. Am. Chem. Soc. 2005, 127, 10804-10805. Domino coupling relay approach to polycyclic pyrrole-2-carboxylates. 

In essence, these domino-coupling reactions form cyclohexadiene fragments from three two-carbon fragments. The 1 2 coupling of norbomene and iodobenzene discovered by Catellani and Chiusoli can also be adopted to couple norbomene with /3-bro-mostyrene.f hi an attempt to apply this Pd-catalyzed [2+2 + 2] assembly for an alternative and more productive access to Hopf s trifoliaphane, a 1 2 mixture of [2.2]paracyclophan-l-ene and l-bromo[2.2]paracyclophan-l-ene was tfeated with palladium acetate under Jeffery conditions. The main product was the hydrocarbon consisting of three [2.2]paracyclophane units linked by a common bicyclo[3.3.0]octene unit (Scheme Apparently, the key intermediate formed via a palladacycle preferen-... 

Based on the Cul-catalyzed C-N coupling reaction, Buchwald et al. developed a domino coupling/cyclization process for synthesizing substituted pyrroles 119 from vinyl halides 117 and Boc-protected amines (Scheme 42) [78]. When Boc-protected... 

Domino couplings of a,j8-enones, alkynes and alkenes are catalyzed by Ni(COD)2 and assisted by ZnCl2 to give the corresponding cyclic products [167]. Linear triquinane is obtained conveniently in one pot. 

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