This report discloses a novel concise synthesis of a series of 3-hydroxypyrazoles 5 via a tandem Ugi/debenzylation /hydrazine-mediated cyclization sequence. Herein, n-butyl isocyanide 4b was utilized as an alternative to classical convertible isocyanides enabling high yielding hydrazine-mediated cyclization. Taken together, a novel class of 3-hydroxypyrazoles 5a-5i was synthesized with potential ...

A novel and convenient one-pot asymmetric synthesis of 2- and 2,3-disubstituted tetrahydrofurans has been achieved in 56-81% yields and 86-99% ee from aliphatic and aromatic aldehydes via an allyl/crotyl/alkoxyallylboration-hydroboration-iodination-cyclization reaction sequence.

A formal asymmetric organocatalytic aminohydroxylation reaction of enones has been achieved via an aziridination-double S(N)2 sequence. As a part of the reaction design, the generated amino alcohol products are isolated as the corresponding oxazolidinones in good yields and excellent stereoselectivities.

K(2)CO(3)-mediated reactions of 6-bromo-2-hexenoates and 7-bromo-2-heptenoate with active methylene compounds deliver highly substituted cyclopentane and cyclohexane derivatives, respectively via a sequence of S(N)2-conjugate addition reactions (formal [4 + 1]- and [5 + 1]-annulation) in a diastereoselective manner.

Asymmetric addition of silylacetylenes to meso-oxa- and azabenzonorbornadienes took place in the presence of a cobalt/QuinoxP* catalyst to give the addition products in good yields with high enantioselectivity.

The stereochemical courses of the copper-catalyzed allyl-alkyl coupling between enantioenriched chiral allylic phosphates and alkylboranes were switchable between 1,3-anti and 1,3-syn selectivities by the choice of solvents and achiral alkoxide bases with different steric demands. The reactions with γ-silylated allylic phosphates allow efficient synthesis of enantioenriched chiral allylsilanes with tertiary ...

A synthesis of the Prelog-Djerassi lactone [(+)-1] has been accomplished in three isolations and 57% overall yield from the known vinyl ortho ester 2. A Rh(I)-catalyzed asymmetric hydroformylation/crotylation tandem sequence has been developed and used to set the C2-C4 stereochemistry. A Rh(I)-catalyzed asymmetric hydrogenation was employed to set the C6 ...

In the presence of an allyl alcohol, α-chloroacetophenones undergo an allyloxycarbonylation reaction followed by in situ decarboxylative allylation to selectively afford the corresponding monoallylated ketones via a Pd-catalyzed domino sequence. The scope of the reaction was extended to substituted α-chloroacetophenones as well as various allyl alcohols.

Cognac in the jar! An efficient one-pot sequence for the preparation of γ-lactones is described. Following reduction of α-bromo ester precursors with DIBAL-H and radical cyclization of the resulting O-aluminum acetals, a preparative in-situ Oppenauer-type oxidation of the cyclic O-aluminum acetal using simple aldehydes or ketones gives access to γ-lactones ...

The first enantioselective synthesis of a potent GlyT1 inhibitor is described. A 3-nitroazetidine donor is used in an enantioselective aza-Henry reaction catalyzed by a bis(amidine)-triflic acid salt organocatalyst, delivering the key intermediate with 92% ee. This adduct is reductively denitrated and converted to the target through a short sequence, thereby ...

The characteristics of the spin-trapping reaction in the oxygen radical absorbance capacity (ORAC)-electron spin resonance (ESR) assay were examined, focusing on the kind of spin traps. 2,2-Azobis(2-amidinopropane) dihydrochloride (AAPH) was used as a free radical initiator. The spin adducts of the AAPH-derived free radical were assigned as those of the ...

Highly efficient and simple coupling reactions of benzylic bromides or chlorides with alkenylaluminum reagents catalyzed by NiCl(2)(PPh(3))(2) are reported. The coupling reactions proceed effectively at room temperature employing low loading of catalyst, 0.5 mol% for benzylic bromides having either electron-donating or -withdrawing substituents on the aromatic ring, affording coupling products ...

Nontoxic cyanide source: An unprecedented route to acrylonitriles by employing propargylic alcohols and para-tolylsulfonohydrazide as a combined cyano source has been developed. This efficient and practical cyanation reaction proceeds through an FeCl(3) -catalyzed domino propargylic substitution/aza-Meyer-Schuster rearrangement sequence, the rearrangement process of which is reported for the first time.

Rolling in the deep: An enantioselective synthesis of a marine antibiotic (-)-atrop-abyssomicin C is described. The key steps of the synthetic sequence are the application of dual catalysis in the formation of the cyclohexane core, the gold-catalyzed formation of a tricyclic spirotetronate unit, and a highly efficient eleven-membered ring closure ...

One-pot synthesis of substituted pyrroles by a cascade reaction of azides with Morita-Baylis-Hillman acetates of acetylenic aldehydes is described and the reaction is efficiently mediated by triphenyl phosphine at room temperature. Sodium azide is successfully used to provide N-unsubstituted pyrroles, while alkyl azides afforded the corresponding N-alkylated pyrroles through a ...

(S)-3-(Methylamino)-3-((R)-pyrrolidin-3-yl)propanenitrile (1) is a key intermediate in the preparation of PF-00951966,1 a fluoroquinolone antibiotic for use against key pathogens causing community-acquired respiratory tract infections including multi-drug resistant (MDR) organisms. The current work describes the development of a highly efficient and stereoselective synthesis of 1 in ten steps with an overall ...

Novel catalytic reductions of tertiary and secondary phosphine oxides to phosphines have been developed. Using tetramethyldisiloxane (TMDS) as a mild reducing agent in the presence of copper complexes, PO bonds are selectively reduced in the presence of other reducible functional groups (FGs) such as ketones, esters and olefins. Based on ...

The oxidative dearomatization of 3-(3-alkynyl-4-hydroxyphenyl)propanoic acid is combined with a cascade transition-metal catalyzed cyclization/addition/aromatization/lactamization sequence, which provides a novel approach to prepare furoquinolinone and angelicin derivatives in a convergent and efficient manner.

A convergent reaction sequence involving a reductive coupling and a chiral Brønsted acid catalyzed Nazarov reaction is utilized in a concise formal synthesis of (+)-roseophilin (11 steps via longest linear sequence, 10.2% yield, 95% ee).

A sequence of acetamide directed oxidative Heck reaction and deacetylation-diazotation-Heck coupling allows the traceless removal of the acetamide group and its dual exploitation as a catalyst directing group and a leaving group.

The asymmetric synthesis of the antibacterial natural product, streptophenazine G, has been achieved by employing asymmetric alkylation and asymmetric aldol reactions using chiral oxazolidinones as the key steps. The originally proposed structure for streptophenazine G has been revised, and its absolute configuration has been determined to be 1'S,2'R,6'S. The asymmetric ...

The combination of different types of cobalt-catalyzed transformations in one-pot procedures is described. One of the key building blocks, a boron-functionalized isoprene derivative (boroprene), led to the realization of four-component reaction sequences comprising the cobalt-catalyzed Diels-Alder and a 1,4-hydrovinylation reaction. Eventually, a reaction sequence including a cobalt-catalyzed Diels-Alder reaction, a ...

Access to sulfondiimines: The oxidative one-pot chlorination-imination sequence of in situ generated free sulfilimines by N-chlorosuccinimide (NCS) allows the preparation of N-monosubstituted sulfondiimines under mild reaction conditions with excellent functional-group tolerance (see scheme, Mes=2,4,6-trimethylphenylsulfonyl).

Lepadiformine A, B, and C were synthesized in an enantiomerically pure form using a reductive cyclization strategy. N-Boc α-amino nitriles were deprotonated and alkylated with enantiomerically pure dibromides to afford the first ring. The products were manipulated to introduce phosphate leaving groups, and subsequent reductive lithiation followed by intramolecular alkylation ...

A concise, enantioselective synthesis of (+)-crocacin C is described, featuring a highly diastereoselective mismatched double asymmetric δ-stannylcrotylboration of the stereochemically demanding chiral aldehyde 9 with the bifunctional crotylborane reagent (S)-E-10. The total synthesis of (+)-crocacin C was accomplished in seven steps (longest linear sequence) starting from commercially available precursors.

A facile synthetic approach for the synthesis of 1,8-naphthyridine-4(1H)-one derivatives via a catalyst free and Pd-supported tandem amination sequence is developed and described. In a case of aliphatic amines reaction proceeds in a catalyst free mode, however anilines demand Pd-supported reaction conditions.

In theories of spin-dependent radical pair reactions, the time evolution of the radical pair, including the effect of the chemical kinetics, is described by a master equation in the Liouville formalism. For the description of the chemical kinetics, a number of possible reaction operators have been formulated in the literature. ...

A practical method for the synthesis of 1,3-aminohydroxyacetone synthons was developed, and their utility in the organocatalytic asymmetric aldol reaction was demonstrated in a short synthesis of aza-sugars.

The first synthesis of tetracyclic alkaloid virosine A is reported. The natural alkaloid was prepared in only 13 steps, in an enantioenriched form. The azabicyclo[2.2.2]octane core was efficiently assembled using a key Vilsmeier-Haack and Mannich cyclizations sequence performed in one-pot.

Three new compounds; epi-mukulin, (Z)-Δ (1,2) dehydroguggulsterone and Δ (6,7)dehydro-20-hydroxygugglsterone were isolated from the n-hexane-soluble fraction (HSF) of the methanol extract of guggul, the oleogum resin of Commiphora wightii together with six known compounds: diasesartemin, (+)-epi-magnolin, (+)-diayangambin, gugglsterol I, (E)-guggulsterone and (Z)-guggulsterone. Their structures were elucidated on the basis of ...

The first asymmetric synthesis of β-trifluoromethylated pyrroline carboxylates has been achieved by organocatalytic conjugated addition of adamantyl glycine imine to β-trifluoromethylated enones, followed by a deprotection/cyclization/dehydration sequence.

The effect of moderate intensity pulsed electric fields (MIPEF) on the bioactive compounds (total polyphenol, lycopene and vitamin C content) as well as on the antioxidant capacity of tomato fruit was studied. The MIPEF treatment conditions were optimized to obtain tomato fruit with a high content of bioactive compounds. Tomato ...

The exposure of guanine in the oligonucleotide 5'-d(TCGCT) to one-electron oxidants leads initially to the formation of the guanine radical cation G(•+), its deptotonation product G(-H)(•), and, ultimately, various two- and four-electron oxidation products via pathways that depend on the oxidants and reaction conditions. We utilized single or successive multiple ...

An efficient enantioselective synthesis of cermizine D has been developed that exploits the use of a common intermediate to access over 85% of the carbon backbone. Key steps include an organocatalyzed heteroatom Michael addition, a diastereoselective alkylation with α-iodomethyl phenyl sulfide, a conjugate addition to a vinyl sulfone species, and ...

Both enantiomers of Garner's aldehyde (3) are prepared from the same alkene 4 by catalytic asymmetric hydroformylation.

Enantioselective synthesis of β-trifluoromethylated pyrrolines has been developed by the organocatalyzed-conjugated addition of nitromethane to β-trifluoromethylated enones, followed by a nitro-reduction/cyclization/dehydration sequence in a one-pot procedure with 97-98% ees.

An original tribromide derivative based, palladium-catalyzed synthesis of 3-substituted-1(2H)-isoquinolone is described based on a regioselective Suzuki-Miyaura C-C coupling on o-halo-(2,2-dihalovinyl)-benzene followed by a palladium catalyzed amination-carbonylation-cyclization reaction. This sequence efficiently proceeds to build up isoquinolone in fair to good yields over a one-pot 3-bond synthesis reaction.

Parham cyclization -intermolecular alpha-amidoalkylation sequence results in the facile enantioselective synthesis of 12b-substituted isoindoloisoquinolines (ee up to 95 %), using BINOL-derived Brønsted acids. alpha-Amidoalkylation of indole occurs through the formation of a chiral conjugate base / bicyclic quaternary N-acyliminium ion pair.

Expanding upon the recently developed aminocatalytic asymmetric indole-2,3-quinodimethane strategy, a straightforward synthesis of structurally and stereochemically complex tetrahydrocarbazoles has been devised. The chemistry's complexity-generating power was further harnessed by designing a multicatalytic, one-pot Diels-Alder/benzoin reaction sequence to stereoselectively access trans-fused tetracyclic indole-based compounds having four stereogenic centers with very high ...

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. Highly functionalized tetracyclic fused furoindolines (2) and dihydropyranylindolines (4) are synthesized in moderate to good yields and enantiomeric excesses of up to 87%.

A novel functionalized steroidal BINOL scaffold is produced by via a remarkable sequence of dehydrogenation, chlorination and atroposelective phenolic coupling steps. Its formation is straightforwardly obtained in a one-step synthesis under solid state conditions and in the absence of chiral additives.

The total synthesis of (+)-cyperolone, an eudesmane-derived sesquiterpenoid from Cyperus rotundus, is described. The de novo synthesis was accomplished via a 15 step sequence starting from (R)-(-)-carvone. The synthetic route features a platinum-catalyzed cycloisomerization to rapidly construct the bicyclic core from a 3-silyloxy-1,5-enyne intermediate.

The human mouth is home to a rich assortment of native and transient microorganisms. One of the commonly encountered bacterial species, Streptococcus mutans, was shown to generate the novel hybrid polyketide-nonribosomal peptide metabolite mutanobactin A (1). We have characterized three new analogues, mutanobactins B-D (2-4), and subjected these compounds to ...

The synthesis of planar chiral strong Brønsted acid organocatalysts derived from [2.2]paracyclophane is described. Resolution was accomplished according to a modified protocol involving pseudo-ortho-substituted [2.2]paracyclophane-based sulfoxides for the synthesis of three new sulfonic acids. The first planar chiral phosphoric acid diester was obtained from the corresponding phenyl-substituted diol derived from ...

An effective total synthesis and assignment of the absolute configuration of the architecturally challenging compound (+)-scholarisine A has been achieved via a 20-step sequence. Highlights include a reductive cyclization involving a nitrile and an epoxide, a modified Fischer indole protocol, a late-stage oxidative lactonization, and an intramolecular cyclization leading to ...

A method to convert 2-hydroxy glycal ester to the corresponding 2-deoxy-2-C-alkyl glycal in a facile manner, through key reactions of (i) C-allylation at C-1; (ii) Wittig reaction and (iii) Cope rearrangement of a 1,5-diene derivative, is reported. alpha-Anomer of 1,5-diene derivative underwent Cope rearrangement to afford 2-deoxy-2-C-glycal derivative, whereas the ...

Several diversity-oriented syntheses of N-fused polycyclic heterocycles have been demonstrated but most of them are based on point diversity within the same library and usually involve time-consuming sequential multistep syntheses, which also suffer from low yields and/or poor precursor scopes. We have developed a new strategy for the syntheses of ...

A multicomponent reaction (MCR) based on a cyclohydrocarbonylation (CHC) driven by hydroformylation was set up towards the efficient diastereoselective preparation of oxazolo-piperidines (4a-e) and -azepines (7a-d). The bicyclic oxazolidines were obtained from chiral N-alkenyl amino alcohols via transient cyclic iminium intermediates that underwent an intramolecular cyclization from the appendant oxygen. ...

An effective synthesis of (+)-conduritol F, (+)-chiro- and (+)-epi-inositols from naturally available (+)-proto-quercitol is described. This synthetic method provides a concise synthesis of cyclitols in enantiomerically pure form. Of the synthesized cyclitols, (+)-conduritol F potently inhibits type I α-glucosidase with an IC(50) value of 86.1μM, which is five times greater ...

BACKGROUND & AIMS: The absence of light protection of neonatal total parenteral nutrition (PN) contributes to the generation of 4-hydroxynonenal and peroxides. 4-Hydroxynonenal is suspected to be involved in PN-related liver complications. Aims: To find a practical modality to reduce 4-hydroxynonenal in PN and assess in vivo the impact of PN ...