Showing papers in "Organic Letters in 2012"

TL;DR: Cationic ruthenium(II) complexes enabled oxidative C-H bond functionalizations with anilines bearing removable directing groups and provided general access to various bioactive indoles.

TL;DR: Improved conditions for the generation of iminium ions from tetrahydroisoquinolines that allow for versatile nucleophilic trapping are reported, providing access to a diverse range of functionality under mild, anaerobic reaction conditions as well as mechanistic insights into the photoredox cycle.

TL;DR: The photoredox-catalyzed coupling of N-aryltetrahydroisoquinoline and Michael acceptors was achieved using Ru(bpy)(3)Cl(2) or [Ir(ppy)(2)(dtb-bpy)]PF(6) in combination with irradiation at 455 nm generated by a blue LED, demonstrating the trapping of visible light generated α-amino radicals.

TL;DR: Ruthenium-catalyzed oxidative C-H bond olefination of N-methoxybenzamides using an oxidizing directing group with a broad substrate scope is reported.

TL;DR: An inexpensive cationic ruthenium(II) catalyst enabled the expedient synthesis of isocoumarins through oxidative annulations of alkynes by benzoic acids and was shown to proceed by rate-limiting C-H bond rUThenation.

TL;DR: An efficient Rh(III)-catalyzed direct C-H amination of N-pivaloyloxy benzamides with N-chloroamines proceeding at room temperature was achieved and the versatile directing group allows for selective mono- and diamination.

TL;DR: Regio- and stereoselective Cu-catalyzed addition of the above hypervalent iodine reagent to alkynes and alkenes was achieved, andAlkenes react faster than alkynes emphasizing the electrophilic character of the addition reaction.

TL;DR: An aerobic visible-light driven photoredox catalytic formation of 2-substituted benzothiazoles through radical cyclization of thioanilides has been accomplished.

TL;DR: A cationic ruthenium(II) complex enabled efficient oxidative alkenylations of anilides in water as a green solvent and proved applicable to double C-H bond functionalizations of (hetero)aromatic amides with ample scope.

TL;DR: Aromatic and heteroaromatic ketoximes underwent cyclization with alkynes in the presence of a catalytic amount of [{RuCl(2)(p-cymene)}(2)] and NaOAc to give isoquinoline derivatives in good to excellent yields in a highly regioselective manner.

TL;DR: An Fe(III)/NaBH(4)-mediated reaction for the functionalization of unactivated alkenes is described defining the alkene substrate scope, establishing the exclusive Markovnikov addition, and exploring a range of free radical traps.

TL;DR: A new bifunctional probe based on a pyrene-amino acid conjugate for the differential response of Al(3+) and H(+) was demonstrated for the first time.

TL;DR: This site-specific allylation method is applicable to all primary, secondary, and tertiary alkyl acids and exhibits wide functional group compatibility.

TL;DR: A reaction based fluorescence turn-on strategy for hydrogen sulfide (H(2)S) was developed based on a H( 2)S-specific Michael addition-cyclization sequence and the probes showed good selectivity and sensitivity for Hydrogen sulfide.

TL;DR: Bordwell's method of overlapping indicators was used to determine the pK(a) values of some of the most popular (thio)urea organocatalysts via UV spectrophotometric titrations, which may lead to a better understanding of noncovalentOrganocatalysis and may aid in future catalyst development.

TL;DR: The photocatalytic reaction of o-methylthio-arenediazonium salts with alkynes yields substituted benzothiophenes regioselectively through a radical annulation process through green light irradiation of eosin Y.

TL;DR: A Rh(III)-catalyzed direct aromatic C-H amination is achieved using N-chloroamines as a reagent and a one-pot amination protocol involving in situ chlorination of the secondary amines is developed.

TL;DR: An unprecedented aroylation at the ortho C-H bond with respect to a directing group has been accomplished via a Pd(II)-catalyzed cross dehydrogenative coupling approach using alkylbenzene as the synthetic equivalent of an aroYL moiety.

TL;DR: Compounds 1-5 exhibited potent anti-HSV (herpes simplex viruses) activity and a hypothetical biogenetic pathway for houttuynoids A-E was proposed.

TL;DR: A fluorescent turn-on probe for Cys/Hcy based on inhibiting the C═N isomerization quenching process by an intramolecular hydrogen bond was reported, which exhibited higher selectivity toward Cys /Hcy over other amino acids as well as thiol-containing compounds.

TL;DR: Ratiometric imaging of Cu(2+) in living cells is demonstrated by using novel FRET ratiometric fluorescent chemodosimeters, which exhibit several favorable features, including a large variation in the emission ratio, well-resolved emission peaks, high sensitivity, high selectivity, low cytotoxicity, and good cell membrane permeability.

TL;DR: The reaction-based relay recognition of fluoride and cyanide anions was demonstrated for the first time, with rapid response and unique triple output modes in either of two sequential sensing events.

TL;DR: Reaction with cyclopropylmethyl bromide resulted in ring-opening products, suggesting the reaction involves a radical pathway.

TL;DR: The synthesis of architecturally complex polycyclic fused indolines is achieved in a chemo-, regio-, and stereodefined manner, via an enantioselective gold-catalyzed cascade hydroindolination/iminium trapping synthetic sequence, in moderate to good yields and enantiomeric excesses.

TL;DR: Various aromatic and heteroaromatic aldehydes reacted with activated alkenes to give substituted alkene derivatives in a highly regio- and stereoselective manner to give unusual four-membered cyclic ketones or a polycyclic isochromanone derivative via a photochemical rearrangement.

TL;DR: A highly selective fluorescent chemodosimeter based on rhodamine is synthesized which undergoes Cu(2+) driven hydrolysis in aqueous media to produce fluorescence turn-on changes with a detection limit up to the nanomolar range.

TL;DR: An efficient catalytic decarboxylative acylation of unactivated sp(2) (alkenyl) C-H bonds has been developed and is proposed to proceed via a cyclic vinylpalladium intermediate, facilitating the decar boxylative dehydrogenative process with enamide coupling partners.

TL;DR: A metal-free C-H oxidation for the construction of allylic esters has been developed using a commercially available and inexpensive catalyst and oxidant and readily available starting materials, rendering the methodology a useful alternative to other approaches typically employed in the synthesis of allies.

TL;DR: The palladium-catalyzed C-H fluorination of 8-methylquinoline derivatives with nucleophilic fluoride is reported, which involves the use of AgF as the fluoride source in combination with a hypervalent iodine oxidant.

TL;DR: A mild and practical protocol for the copper-mediated trifluoromethylation of aryl and heteroaryl boronic acids using NaSO(2)CF(3) (Langlois' reagent) and TBHP is described.