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Multiply substituted pyrroles are found in medicines, natural products, and functional materials. A general method for introducing functionality on the pyrrole ring is thus required. Herein, a regiocontrolled halogen dance reaction and an in situ transmetalation of α-functionalized bromopyrroles are reported. Selective generation of the isomeric pyrrolylmetal species was achieved by using an ethyl ester or a phenyl group at the α-position of the pyrrole and by switching between the halogen dance reaction and in situ transmetalation. These reactions proceeded smoothly when an N , N -dimethylsulfamoyl group was attached to the pyrrole nitrogen atom, providing the corresponding products in 68% to quantitative yields on 1-mmol scale. This method was applicable to the formal synthesis of Kendine 91. [ABSTRACT FROM AUTHOR]

Circular dichroism (CD) studies on poly(1,4‐phenylene)s bearing a chiral side chain in the aggregated conditions were carried out. Little CD was observed in a solution form, while addition of a poor solvent into the polyphenylene solution induced aggregation and a strong CD was observed, accordingly. Applying the controlled degree of polymerization (DP) of poly(1,4‐phenylene) in the use of bidentate diphosphine Chiraphos as a ligand for the nickel catalyst, the relationship of DP with CD strength was studied to reveal to show the highest CD at the DP=84 (gabs=ca. 2×10−2). It was also found that the related aggregation was observed in good solvent 1,2‐dichloroethane upon standing the solution at 4 °C for 3–23 days to observe gabs=ca. 10−1. Studies on the substituent effect of poly(1,4‐phenylene) suggested that CD behaviors were dependent on the type of non‐chiral substituent on the aromatic ring as well as the side‐chain chirality. [ABSTRACT FROM AUTHOR]

A biphenyl derivative in which two benzene rings are strapped with two chains is prepared. The synthesized product shows molecular asymmetry, which was confirmed by HPLC analysis with chiral column and named as winding vine‐shaped biphenyl. The synthesis of such vine shaped molecule was performed by ring‐closing metathesis or alternatively by annulation with nosylated ethylenediamine. The structure of the obtained product was confirmed by X‐ray crystallographic analysis. The absolute configuration of the molecular asymmetry was assigned after leading to the corresponding camphor sulfonamide through denosylation and re‐amidation process. [ABSTRACT FROM AUTHOR]

This document presents the results of a study on the regioselective deprotonation of brominated pyridylthiophene compounds. The researchers found that the position of deprotonation could be switched by adding DMPU as a Lewis base, allowing for the selective deprotonation of each proton on the thiophene moiety. The subsequent halogen dance reaction resulted in the synthesis of four iodinated isomers from a single starting material. This method has potential applications in the synthesis of various substituted pyridylthiophene derivatives. The study was conducted at NAIST and supported by the ARIM Program of MEXT, Japan. [Extracted from the article]

This article explores the use of nickel thiocyanate complexes as catalysts for cross-coupling reactions in organic synthesis. The authors investigate the synthesis of different (hetero)biaryls using these catalysts and highlight their potential applications in the production of biologically active compounds and electronic materials. The study also examines the impact of various phosphine ligands on the polymerization of thiophenes and phenylenes. The results demonstrate that the nickel thiocyanate complexes are effective catalysts for cross-coupling polymerization reactions. These complexes are stable and easy to prepare, making them suitable for various syntheses and polymerizations. [Extracted from the article]

A total synthesis of lamellarins U and A3 is described. The synthesis features the interruption of a halogen dance reaction of a metalated α,β-dibromopyrrole. The pyrrolylmagnesium reagent, generated by deprotonative metalation by using (TMP)MgCl·LiCl (TMP = 2,2,6,6-tetramethylpiperidide) as the base, was transmetalated to the corresponding organozinc species without causing the halogen dance reaction, which underwent a Negishi coupling to incorporate an aryl group onto the pyrrole ring. The arylated α,β-dibromopyrrole was then converted into lamellarins U and A3 through an α-selective halogen–magnesium exchange followed by carboxylation and subsequent palladium-mediated cyclization. The late-stage introduction of another aryl group was performed using a Kosugi–Migita–Stille coupling to provide lamellarins U and A3. [ABSTRACT FROM AUTHOR]