9‐Stannafluorenes: 1,4‐Dimetal Equivalents for Aromatic Annulation by Double Cross‐Coupling

Rolling circle amplification (RCA) has been widely used as an isothermal DNA amplification technique for diagnostic and bioanalytical applications. Because RCA involves repeated copying of the same circular DNA template by a DNA polymerase thousands of times, we hypothesized there exist DNA sequences that can function as optimal templates and produce more DNA amplicons within an allocated time. Herein we describe an in vitro selection effort conducted to search from a random sequence DNA pool for such templates for phi29 DNA polymerase, a frequently used polymerase for RCA. Diverse DNA molecules were isolated and they were characterized by richness in adenosine (A) and cytidine (C) nucleotides. The top ranked sequences exhibit superior RCA efficiency and the use of these templates for RCA results in significantly improved detection sensitivity. AC-rich sequences are expected to find useful applications for setting up effective RCA assays for biological sensing.

Section: Double Cross‐coupling Reactions Of 9‐stannafluorenesmentioning

confidence: 86%

Section: Palladium‐catalyzed Double Cross‐coupling Reactions Formimentioning

confidence: 99%

Optimal DNA Templates for Rolling Circle Amplification Revealed by In Vitro Selection

Mao

Liu

Tram

et al. 2015

“…A new aromatic annulation through a Pd‐catalyzed double cross‐coupling reaction of 9‐stannafluorenes and 1,2‐dihaloarenes has been reported by Shimizu and co‐workers 70. By using [Pd(P t Bu 3 ) 2 ] (5 mol %) in THF at 60 °C, an efficient double cross‐coupling reaction of 9,9‐dimethyl‐9‐stannafluorene ( 167 ) with 1,2‐dibrobenzene produced the expected triphenylene product ( 168 ) in 90 % yield (Scheme ).…”

Section: Cross‐coupling Reactionsmentioning

confidence: 92%

“…The annulation of vicbis(pinacolatoboryl)phenanthrene (156 c) with 2,2'-dibromo-1,1'-biphenyl (159) and 2,2'-dibromo-3,3'-bithiophene (160) also underwent the Pd-catalyzed double cross-coupling using K 3 A new aromatic annulation through a Pd-catalyzed double cross-coupling reaction of 9-stannafluorenes and 1,2-dihaloarenes has been reported by Shimizu and co-workers. [70] By using [Pd(PtBu 3 ) 2 ] (5 mol %) in THF at 60 8C, an efficient double cross-coupling reaction of 9,9-dimethyl-9-stannafluorene (167) with 1,2-dibrobenzene produced the expected triphenylene product (168) in 90 % yield (Scheme 54 a). This reaction condition can be compatible with various dibromoheteroarenes, giving a variety of triply-annulated PHAHs in good to excellent yields.…”

Section: Cross-coupling Reactions Double Cross-coupling Reactionsmentioning

confidence: 99%

Metal‐Catalyzed Annulation Reactions for π‐Conjugated Polycycles

Jin

Zhao

Asao

et al. 2014

157

The progress of the metal-catalyzed annulation reactions toward construction of various π-conjugated polycyclic cores with high conjugation extension is described. This article gives a brief overview of various annulation reactions promoted by metal catalysts including C-H bond functionalization, [2+2+2] cycloaddition, cascade processes, ring closing metathesis, electrophilic aromatization, and various cross-coupling reactions. A variety of conjugated polycycles with planar, bowl-shaped, and helical structures have been constructed in high efficiency and selectivity.

“…The spectroscopic data are in agreement with those reported in the literature. [7] Representative procedure for a Suzuki cross-coupling reaction of 6 using SPhos (Scheme 2)…”

Section: Methodsmentioning

confidence: 99%

Modular Synthesis of Phenanthro[9,10‐c]thiophenes by a Sequence of CH Activation, Suzuki Cross‐Coupling and Photocyclization Reactions

Schnapperelle

Bach

2014

A total number of 15 different 3,4-diarylthiophenes were synthesized, which bear a chlorine atom in ortho-position of one of the aryl substituents. One aryl group was introduced by an oxidative cross-coupling reaction, involving a CH activation at C4(3) of the thiophene core. The other aryl group was in most cases introduced by a Suzuki cross-coupling reaction, which succeeded the oxidative cross-coupling step. Photocyclization reactions of the 3,4-diarylthiophenes were performed in a solvent mixture of benzene and acetonitrile (50:50 v/v) at λ=254 nm and proceeded to the title compounds in yields of 60-82 %. The selectivity of the photocyclization was determined at the ortho-chloro-substituted aryl ring by the position of the chlorine substituent. At the other ring, a single regioisomer was observed for phenyl and para-substituted phenyl groups. For 2-naphthyl and ortho-substituted phenyl rings a clear preference was observed in favor of a major regioisomer, while meta-substitution in the phenyl ring led to a about 1:1 mixture of 5- and 7-substituted phenanthro[9,10-c]thiophenes. Mechanistically, the photocyclization is likely to occur as a photochemically allowed, conrotatory [(4n+2)π] process accompanied by elimination of HCl. It was shown for two phenanthro[9,10-c]thiophene products that they can be readily brominated in positions C1 and C3 (74-77 %), which in turn allows for further functionalization at these positions, for example, in the course of halogen-metal exchange and polymerization reactions.