Methoxy iodobenzene

Scheme 36, A and Turnover numbers up to approximately 500,000 were reported for the reaction of iodobenzene with methyl acrylate and an impressive nnmber (about 100,000) was also achieved with bromobenzene and 4-methoxy-bromobenzene. Characteristic featnres of these tridentate PCP catalysts are thermal stability and air stability. A competitive experiment, including 4-bromoiodobenzene, iodobenzene, 4-methyliodoben-zene, and 4-methoxy-iodobenzene with methyl acrylate provided a linear correlation with Hammet cr-valnes, which, however, exhibited a low p valne (1.39). It was concluded that nucleophilic aromatic substitution is not rate determining, bnt a snbsequent step with different electronic requirements, such as alkene insertion, may acconnt for this observation. Chlorobenzene could not be coupled with these catalyst. Very recently, Milstein s group reported new cyclopalladated, phosphine-free imine complexes as catalysts in the Heck arylation reaction (Scheme 36, The new dimeric imine complexes show... 

A flask was charged with 4-bromo-iodobenzene (0.079 mol), 4-methoxy-2-methyl-phenyl boronic acid (0.087 mol), palladium acetate (0.004 mol), and triphenyl phosphine (0.008 mol) and then treated with 200 ml acetone and 250 ml 2M NaHCO i. The mixture was refluxed at 65°C for 18 hours and was then treated with water and diethyl ether and the organic layer isolated. This layer was washed with 40 ml saturated sodium chloride solution and water, dried over MgSC>4, filtered, and concentrated. The residue was purified by column chromatography using silica gel with CH2C12/ hexane, 1 1, and then recrystallized in / , 7 3, respectively, and 16.4 g of product isolated. 

Iodo-4-methoxy-4,7,7-trimethylbicyclo[4.1. OJheptane, 3406 Iodobenzene, 2242 Iododisilane, 4538 2(2-Iodoethyl)-1,3-dioxolane, 1922 1-Iodohexa-2,4-diene, 2387 f 2-Iodopropane, 1248... 

The second special case is formed by the photoreactions of 2,4-dinitro-6-(phenyliodonio)phenolate (266) with several nucleophiles759. Upon irradiation of this fairly stable zwitterion in methanol, 6-methoxy-2,4-dinitrophenol is formed in 65% yield. Photoreaction with pyridine affords 2,4-dinitro-6-pyridiniophenolate (85%) and irradiation in the presence of phenyl isothiocyanate in acetonitrile affords a mixture of two stereoisomeric 2-phenylimino-5,7-dinitro-1,3-benzoxathioles (269) (71%) which could not be separated. The reaction starts with attack of the nucleophile on the positively charged iodine atom, leading to an iodinane (267) and proceeds by expulsion of iodobenzene. The mechanism is illustrated for phenylisothiocyanate, a case in which the substitution product (268) can undergo further photocyclization to a benzoxathiole derivative (269) (equation 196). 

A series of phenanthrenes and 9,10-dihydrophenanthrenes mimics have been synthesized by DellaGreca et al. The key step is the cross-coupling of l-(2-iodo-5-methoxy)phenyl-ethanol (822) with variously substituted iodobenzenes by zerovalent nickel (Scheme 16) [430-432]. 

A tributylstannyl group can also be introduced via transmetalation. Collins trans-metalated the trimethylsilyl group of the l,2,4-triazolo[4,3-/>]pyridazine 162 to the corresponding tributylstannane 163 using (Ihi Snj O [35]. Subsequent Stille reaction of 163 with iodobenzene in the presence of Pd(PPh3)4 in DMF at 100°C resulted in the formation of 164, albeit in a low overall yield. In the same paper, a reverse approach was presented in which a brominated triazolopyridazine 165 reacted with 2-tributylstannyl-1,3-oxazole to yield 6-[(l-methyl-l//-l,2,4-triazol-5-yl)methoxy]-7-(l,3-oxazol-2-yl)-3-phenyl[l,2,4]triazolo[4,3-Z ]pyridazine 166 in 37% yield (23% of starting compound was also recovered). 

Dicarbonyl compounds are formed from the reaction of silyl enol ethers with methyl vinyl ketones in the presence of BF3 OEt2 and an alcohol (eq 9). a-Methoxy ketones are formed from a-diazo ketones with BF3-OEt2 and methanol, or directly from silyl enol ethers using iodobenzene/BF3-OEt2 in methanol. ... 

In some instances, the unsymmetrical coupling reaction of an arylcopper(I) reagent with the aryl halide can be carried out without the or/Ao-coordinating substituents. It has been shown that 2-thienylcopper(l) and 2-furylcopper(l) readily couple with iodobenzene or 4-iodoanisole to give 2-phenylthiophene (50%) and 2-(4-methoxy... 

Methoxy-, methyl- and bromo-substituted indoles also participated readily in a tandem palladium/copper catalyzed C—H functionalization/ C—H insertion reaction with ethyl diazoacetate (147) and iodobenzene (146) (2015JAC4435). More significantly, the authors were able to illustrate that a copper catalyzed N—H insertion could also be performed in tandem with the C—H functionalization. In this case, 4-aminoindole (149) smoothly underwent coupling to give 150 in 79% yield. 

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