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Imidazo[1,5-a]pyrazines 1undergo regioselective C3-metalation and C5/C3-dimetalation to afford a range of functionalized derivatives 2a−2g(Table 1), and 4a−4d(Table 2). Under similar conditions, the C3-methyl derivatives 2aand 5undergo surprising regioselective C5-deprotonation to afford, after electrophile quench, products 4b and 6a−6p(Table 3), results that are rationalized by quantum mechanical calculations. Benzamide 7b, obtained from such metalation chemistry followed by Suzuki cross coupling, undergoes directed remote metalation-cyclization to afford 8, representing the hitherto unknown triazadibenzo[cd,f]azulen-7(6H)-one tricyclic ring system. [ABSTRACT FROM AUTHOR]

Starting from commercially available (+)-sclareolide, the first synthesis of zerumin B was achieved by a concise, highly efficient pathway featuring stereoselective addition of a new silyloxyfuryltitanium reagent to an aldehyde intermediate and silyloxyfuran oxyfunctionalization as key steps. The synthesis established the relative and absolute configuration of zerumin B along with its identity with a purportedly new diterpenoid isolated from the plant Renealmia alpinia. [ABSTRACT FROM AUTHOR]

An iterative procedure gives 1,3,5-phenyl-linked dendrons of up to the fourth generation and enables the formation of different generations of iridium(III) complex-cored dendrimers. The convergent synthesis uses N,N′-1,8-napthyl-3,5-dibromophenylboronamide as the key building block. The iterative synthesis cycle involves deprotection of the boronamide-focused dendron to form a boronic acid and subsequent Suzuki coupling either with the N,N′-1,8-napthyl-3,5-dibromophenylboronamide to give the next dendron generation or with an activated core to form a dendrimer. [ABSTRACT FROM AUTHOR]

Reaction of the half-sandwich complexes MIII(Pc)-(acac) (M = La, Eu, Y, Lu; Pc = phthalocyaninate; acac = acetylacetonate) with the metal-free N-confused 5,10,15,20-tetralds[(4-tert-buryl)phenyl]porphyrin (H2NTBPP) or its N2-position methylated analogue H(CH3)NTBPP in refluxing 1,2,4-trichlorobenzene (TCB) led to the isolation of MIIII(Pc)-(HNTBPP) (M = La, Eu, Y, Lu) or Y,III(Pc)[(CH3)NTBPP] in 8--15% yield. These represent the first examples of sandwich-type rare earth complexes with N-confused porphyrinato ligands. The complexes were characterized with various spectroscopic methods and elemental analysis. The molecular structures of four of these double-decker complexes were also determined by single-crystal X-ray diffraction analysis. In each of these complexes, the metal center is octa-coordinated by four isoindole nitrogen atoms of the Pc ligand, three pyrrole nitrogen atoms, and the inverted pyrrole carbon atom of the HNTBPP or (CH3)NTBPP ligand, forming a distorted coordination square antiprism. For EuIII(Pc)(HNTBPP), the two macrocyclic rings are further bound to a CH3OH molecule through two hydrogen bonds formed between the hydroxyl group of CH3OH and an aza nitrogen atom of the Pc ring or the inverted pyrrole nitrogen atom of the HNTBPP ring, respectively. The location of the acidic proton at the inverted pyrrole nitrogen atom (N2) of the protonated double-deckers was revealed by 1H NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Chemical de-caging has emerged as an attractive strategy for gain-of-function study of proteins via small-molecule reagents. The previously reported chemical de-caging reactions have been largely centered on liberating the side chain of lysine on a given protein. Herein, we developed an allene-based caging moiety and the corresponding palladium de-caging reagents for chemical rescue of tyrosine (Tyr) activity on intracellular proteins. This bioorthogonal de-caging pair has been successfully applied to unmask enzymatic Tyr sites (e.g., Y671 on Taq polymerase and Y728 on Anthrax lethal factor) as well as the post-translational Tyr modification site (Y416 on Src kinase) in vitro and in living cells. Our strategy provides a general platform for chemical rescue of Tyr-dependent protein activity inside cells. [ABSTRACT FROM AUTHOR]

A novel visible-light-induced carboperfluoroalkylation of alkenes using perfluoroalkyl iodides and bromides as Rf sources, leading to isoquinoline-1,3-diones, was developed. This method offers rapid entry to perfluorinated isoquinoline-1,3(2H,4H)-diones from N-alkyl-N-methacryloyl benzamides under mild reaction conditions, allowing for the incorporation of a wide variety of perfluorinated groups such as CF3, C3F7, C4F9, C6F13, C8F17, C10F21, and CF2CO2Et. [ABSTRACT FROM AUTHOR]

A catalytic hydrovinylation of N-acetylenamines with ethylene is reported. This new hydrovinylation reaction is catalyzed by a ruthenium hydride complex, RuHCl(CO)(PCy3)2, providing a series of N-acetylamines with a quaternary carbon center with up to 99% yield. [ABSTRACT FROM AUTHOR]

The synthesis of two novel 2-methylchromone-7-O-rutinosides is reported, and the in vitro biological activities of these compounds and their synthetic precursors have been investigated on the basis of their cytotoxicity against several human tumor cell lines. The synthesis features early stage assembly of the acidic labile glycosidic bond between sugar and 2-methylchromone aglycon under phase transfer catalyzed glycosidation conditions, whereas all the other standard glycosylation conditions specific to a wide array of rutinosyl donors bearing different anomeric leaving groups (e.g., SPh, OC(NH)CCl3, Br, OH groups) failed to furnish any detectable products. [ABSTRACT FROM AUTHOR]

Two novel cyclic hexapeptides containing both anthranilic acid and dehydroamino acid units, sclerotides A (1) and B (2), were isolated from the marine-derived halotolerant Aspergillus sclerotiorumPT06-1 in a nutrient-limited hypersaline medium. Both 1and 2are photointerconvertible and could be interconverted via a radical reaction initiated by direct photoisomerization. Both compounds showed moderate antifungal activity. Compound 2also showed weak cytotoxicity and antibacterial activity. [ABSTRACT FROM AUTHOR]

The article presents a study on the nickel-catalyzed asymmetric reductive coupling of 1, 3-dienes and aldehydes, which offers a useful method for preparing chiral bishomoallylic alcohols in excellent diastereoselectivity and enantioselectivity. The study examines various chiro spiro monophosphorus ligands in the nickel-catalyzed coupling reaction to produced chiral bishomoallylic alcohols. Results reveal that by using nickel complexes with a reducing agent, the high yields alcohol is obtained.