Iodobenzene derivatives

Snieckus and his group members [104] used the known domino Sonogashira/ Castro-Stephens reaction [105, 106] for the synthesis of the natural product pli-cadin (6/1-209), this having been isolated from Psorelia plicata in 1991 [107]. In this synthesis, Pd°-catalyzed reaction of the alkyne 6/1-210 and the iodobenzene derivative 6/1-211 in the presence of Cul led to the furan 6/1-212, which was transformed into 6/1-209 via 6/1-213 (Scheme 6/1.54). There are some discrepancies of the physical data of the natural and the synthetic product thus, it might be possible that the natural product has a different structure. It should also be mentioned that the... 

Representative of recent applications of the reaction to the synthesis of heterocycles are the photodehydrochlorination of chlorobenzo[b]thiophen (347) to give the fused pyrimidone 348,287 the photoelimination of HI from iodobenzene derivatives 349 to give the benzazepines 350,288 and the synthesis of the medium ring aza-heterocycle 351 by irradiation of the chloro precursor 352.289 Included among the many other examples of... 

The palladium catalysed sequential alkylation-alkenylation of 5-iodoquinoline leads to the formation of the quinolooxepin ring system (5.20.), The process, closely related to the Catellani reaction,19 runs through an ort/zo-alkylation - Heck reaction sequence. The preparation of a series of benzoxepines has also been achieved in this manner, starting from such iodobenzene derivatives, where one of the or/7 o-positions was blocked by substitution.20... 

However, for other palladium catalysed reactions of organozinc iodides with electrophiles, THF is a good choice of solvent. The incompatibility of THF and acid chlorides at ambient temperature can also be overcome, in some cases, by the use of a carbonylative cross-coupling in which an iodobenzene derivative is used as the precursor.17... 

Scheme 1.29 Reductive arylation of SWCNTs with iodobenzene derivatives, conversion to zwitterions by sulfonation.

This compound was obtained from BTI and sodium saccharinate. It belongs to a category of iodobenzene derivatives in which two imidyl groups are attached to iodine through nitrogen its main utility was the transfer of a saccharinyl group to the a-position of enolizable ketones. 

Aryl iodides are formed by treating arenediazonium salts with potassium iodide. This is one of the best methods for making iodobenzene derivatives. 

Both halogens in di-bromo- or di-iodobenzene derivatives can be replaced by Li in halogen-Li exchanges. If the two halogens are ortho, aryne formation can occur from the monoexchange product, l-Li-2-X-benzene, although such compounds can be trapped at low T, e.g. ... 

Direct anodic oxidation of iodobenzene and /Mira-methyliodoben-zene did not give the corresponding hypervalent difluorides. Therefore, indirect anodic oxidation was attempted using a chloride ion mediator. In this case, the desired difluoro products are not formed but instead a novel hypervalent iodobenzene derivative, such as 73, having I-F and I-Cl bonds is produced. It was found that difluorina-tion occurs by the reaction of dithioacetals with iodobenzene chlo-rofluorides. Indirect anodic oxidation of dithioacetals by using a catalytic amount of para-methoxyiodobenzene was attempted as shown in Scheme 55 and it was found that desulfurizative difluorina-... 

Three simpler ort/io-substituted iodobenzene derivatives with two alkene moieties in the side chains have been cascade cycUzed to give methylenespiroalkane-annelated indanes (Scheme 26) and bicyclic systems (Scheme 27). This outcome clearly demonstrates that the intramolecular carbopalladations are determined by entropic factors, which always favor the formation of the smaller possible ring sizes. 

Further, silica-supported poly-y-aminopropylsilane transition metal complexes derived from Ni(II), Cu(II) and Co(II) salts were probed in arylation reactions of acrylic acid (16), methyl acrylate (1) and styrene (2) using iodobenzene derivatives. The most efficient catalysis was again observed with the nickel-based recyclable catalyst [23,25]. 

Scheme 12.47 Divergent reaction of -substituted iodobenzene derivatives.

Pt(PPh3)4 reacts with iodobenzene derivatives having OGH2SnBu3 or OGH2SiMe3 substituents at the 2-position to form the 3-oxa-platinacycle 399 (Scheme 55). Oxidative addition of a G-I bond to Pt(0) is followed by intramolecular transmetallation via activation of the G-Sn or G-Si bonds. The reactions proceed smoothly without additives, although intermolecular cross-coupling of aryl triflate with vinyl(tributyl)stannane promoted by the Pt complex requires addition of a base such as K2GO3. 

The palladium-catalyzed self-homocoupling of borylvinyl iodobenzene derivatives, which were available via the selective Suzuki-Miyaura cross-coupling of the gem-diboryl reagents with iodo compounds, resulted in a [4-1-4] cycloaddition, giving selectively dibenzo[a,c]cyclooctatetraenes in good yields (Scheme 8.41) [66]. 

Zhang, H., Wei, J., Zhao, E, Liang, Y., Wang, Z., Xi, Z. (2010). Selective synthesis of dibenzo[a,c]cyclooctatetraenes via palladium-catalyzed [4+4] eycUc homocoupling of boiylvinyl iodobenzene derivatives. Chemical Communications, 46, 7439—7441. 

C-H Bond Functionalization. The direct arylation of 2-ethylthiophene with bromobenzene and iodobenzene derivatives is observed to proceed best with PdBr2 in the presence of bipyridine and Ag2C03 over alternate palladium(II) and Pd(0) sources (eq 37). Optimal yields are obtained with the preformed catalyst. Other heteroarenes have been shown to react with iodoarenes in arylation reactions. 

Scheme 11.15. Catalytic circle of the Sonogashira-Hagihara reaction (Instead of iodoarenes R I, bromo compounds or electrophiles with other leaving groups can be used Cul as cocatalyst can be omitted when iodobenzene derivatives are used.)...

Since 2002, our group broadened the scope of the above reaction from bromopyridine to various l-substituted-3-bromobenzene derivatives. After deprotonation with LiZn(TMP) Bu2 followed by iodination, the corresponding l-substituted-3-bromo-2-iodobenzene derivatives were obtained in high yields (Fig. 22) [54, 74]. 

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