10 research outputs found
gamma-Selective Allylation of (E)-Alkenylzinc Iodides Prepared by Reductive Coupling of Arylacetylenes with Alkyl Iodides
The first examples of Cu-catalyzed gamma-selective allylic alkenylation using organozinc reagents are reported. (E)-Alkenylzinc iodides were prepared by Fe-catalyzed reductive coupling of terminal arylalkynes with alkyl iodides. In the presence of a copper catalyst, these reagents reacted with allylic bromides derived from Morita-Baylis-Hillman alcohols to give 1,4-dienes in high yields. The reactions are highly gamma-selective (generally gamma/alpha > 49:1) and tolerate a wide range of functional groups such as ester, cyano, keto, and nitro
Z-Selective Olefin Synthesis via Iron-Catalyzed Reductive Coupling of Alkyl Halides with Terminal Arylalkynes
Selective catalytic synthesis of Z-olefins has been challenging. Here we describe a method to produce 1,2-disubstituted olefins in high Z selectivity via reductive cross-coupling of alkyl halides with terminal arylalkynes. The method employs inexpensive and nontoxic catalyst (iron(II) bromide) and reductant (zinc). The substrate scope encompasses primary, secondary, and tertiary alkyl halides, and the reaction tolerates a large number of functional groups. The utility of the method is demonstrated in the synthesis of several pharmaceutically relevant molecules. Mechanistic study suggests that the reaction proceeds through an iron-catalyzed anti-selective carbozincation pathway
A Monometallic Iron(I) Organoferrate
Tetra-n-butylammonium (TBA) (eta(6)-biphenyl)diphenyfferrate was formed unexpectedly in the reaction of (TBA)(2)[Fe4S4Cl4] with an excess of phenyllithium. This complex belongs to a novel type of organoferrate
γ‑Selective Allylation of (<i>E</i>)‑Alkenylzinc Iodides Prepared by Reductive Coupling of Arylacetylenes with Alkyl Iodides
The first examples of Cu-catalyzed
Îł-selective allylic alkenylation using organozinc reagents are
reported. (<i>E</i>)-Alkenylzinc iodides were prepared by
Fe-catalyzed reductive coupling of terminal arylalkynes with alkyl
iodides. In the presence of a copper catalyst, these reagents reacted
with allylic bromides derived from Morita–Baylis–Hillman
alcohols to give 1,4-dienes in high yields. The reactions are highly
γ-selective (generally γ/α > 49:1) and tolerate
a wide range of functional groups such as ester, cyano, keto, and
nitro
Synthetic Approaches to Functional Derivatives of Cycl[3.2.2]Azine-1,2-Dicarboxylic Acid - Perspective Building Blocks for pi-Extended Macrocyclic Compounds
One of the actual goals in the field of macrocyclic research is to provide accessible chemically robust compounds with absorption in the NIR spectral region. This requirement can be fulfilled in the case of tetrapyrrolic derivatives such as porphyrins, phthalocyanines etc with extended system of electronic conjugation. In this short review, we focus on the available approaches for the synthesis of cycl[3.2.2]azine-1,2-dicarboxylic acid functional derivatives - an emerging class of - extended tetrapyrrolic macrocycle precursors
Nucleosome Positioning in Saccharomyces cerevisiae
Summary: The DNA of eukaryotic cells is spooled around large histone protein complexes, forming nucleosomes that make up the basis for a high-order packaging structure called chromatin. Compared to naked DNA, nucleosomal DNA is less accessible to regulatory proteins and regulatory processes. The exact positions of nucleosomes therefore influence several cellular processes, including gene expression, chromosome segregation, recombination, replication, and DNA repair. Here, we review recent technological advances enabling the genome-wide mapping of nucleosome positions in the model eukaryote Saccharomyces cerevisiae. We discuss the various parameters that determine nucleosome positioning in vivo, including cis factors like AT content, variable tandem repeats, and poly(dA:dT) tracts that function as chromatin barriers and trans factors such as chromatin remodeling complexes, transcription factors, histone-modifying enzymes, and RNA polymerases. In the last section, we review the biological role of chromatin in gene transcription, the evolution of gene regulation, and epigenetic phenomena