Abstract In this work we report the synthesis of new fluorescent analogues strigolactones, their spectroscopic properties and evaluation biological activity both on seeds Orobanche aegyptiaca AM fungus Gigaspora margarita . The has been accomplished according to two different synthetic plans allows introduction various substituents A C rings framework, thus enabling access bioactive molecules with properties.

Indenes constitute an important class of molecules which continue to attract interest from the synthetic organic chemists′ community because not only many natural and compounds embodying indene skeleton display bioactivity or pharmaceutical activity but also indenes find applications in material science, e.g. photovoltaic solar cells preparation new fluorescent materials, metal complexes with special catalytic activity. Many approaches have been exploited last four years build this bicyclic...

A new class of strigolactone analogues has been synthesized. They differ from known molecules, both natural and synthetic origin, in two main features. The conjugated system extends the enol ether bridge to ring, B ring is a heterocycle while C cyclic ketone instead γ-lactone. key step synthesis Nazarov cyclization on activated substrates. Bioassays using Orobanche seeds have revealed that all molecules strongly stimulate germination; particular oxygen containing are most active....

The electrophilic α‐hydrazination (generally referred to as α‐amination) of carbonyl compounds with dialkyl azodicarboxylates is a powerful approach for the preparation synthetically useful intermediates such α‐amino aldehydes and ketones, acids, β‐amino alcohols. Many methods enantioselective have been published in past many new approaches disclosed last decade that deal previously unresolved issues direct α‐branched ketones. field where most significant advances attained thanks approaches,...

A tandem gold(I)-catalyzed rearrangement/Nazarov reaction of enynyl acetates which efficiently provides cyclopenta[b]indol-1-ones as useful precursors for the synthesis natural and bioactive compounds is described. The synthetic potential methodology demonstrated by first total bruceolline H.

The Pd(0)-catalyzed reaction of vinyl triflates from N-alkoxycarbonyl lactams with different boron compounds has been studied. coupling alkenylboronates and arylboronic acids six- seven-membered lactam-derived was feasible under very mild conditions in THF-water employing (Ph3P)2PdCl2 as a catalyst Na2CO3 base, which provided high yields the corresponding 6- or 7-substituted N-alkoxycarbonyl-3,4-dihydro-2H-pyridines N-alkoxycarbonyl-2,3,4,5-tetrahydroazepines. Allylboronates reacted slower...

The Pd-catalyzed coupling reaction of lactam or lactone-derived vinyl triflates and phosphates with α-alkoxydienylboronates gives conjugated alkoxytrienes in which one the double bonds is embedded a heterocyclic moiety. If subjected to mild acidic hydrolysis, these compounds undergo 4π electrocyclization process (Nazarov reaction) furnishes cyclopenta-fused O- N-heterocycles good yields. scope work has been that closely examining role effect both heteroatom heterocycle ring size on outcome...

[reaction: see text] A study on the conversion of lactam-derived vinyl triflates and phosphates into corresponding boronates was carried out. While delta-valerolactam-derived were successfully converted 1,4,5,6-tetrahydropyridine-2-boronic acid pinacol ester derivatives by Pd-catalyzed coupling reaction with both bis(pinacolato)diboron pinacolborane, pyrrolidinone epsilon-caprolactam either did not react or readily reduced. The are thermally stable compounds that efficiently coupled, under...

Abstract The gold(I)‐catalyzed tandem rearrangement/Nazarov reaction of propargylic ester derivatives is a useful strategy for the synthesis cyclopenta‐fused N‐heterocyclic structures present in many natural compounds. Readily available lactams are converted into enol phosphates and triflates coupled to propargyl alcohols under Sonogashira conditions. After acetylation, gold‐catalyzed rearrangement enynyl acetates readily occurs when using 3–5 mol‐% gold(I) catalyst. generates divinyl cation...

The gold(I)-catalyzed cyclization of N-Boc-protected 6-alkynyl-3,4-dihydro-2H-pyridines, prepared by the Sonogashira coupling lactam-derived enol triflates or phosphates, provides vinylogous amides, which are useful intermediates in synthesis natural compounds. Au(I)-catalyzed reaction is carried out with Ph3PAuOTf as a catalyst and proceeds via 6-endo-dig to form vinylgold species that after protodeauration generates cyclic carbamate intermediate. This intermediate most cases not isolated,...

Stille, Suzuki-Miyaura, and Sonogashira cross-coupling reactions were carried out with a glutarimide-derived vinyl phosphate, bearing chiral auxiliary on the N atom, to prepare enantiopure 2-(N-acylamino)-1,3-dienes as partners in Diels-Alder reactions. The cycloadditions performed various dienophiles under thermal conditions, or without Lewis acids. With maleimides, preferential formation of endo cycloadducts was observed, whereas acrylamides exo approach prevailed. Furthermore, latter...

Two new dipeptide isosteres derived from l-leucine and meso-tartaric acid derivatives, named 6-endo-BTL 6-endo-BtL, were inserted in a small peptide by means of SPPS, the conformational features resulting peptides 3 4 studied NMR, IR, molecular modeling techniques. The presence reverse turn conformation was observed all structures, suggesting key role scaffolds as promoters. Peptides did not adopt preferred indicated equilibria between open intramolecular hydrogen-bonded structures....

Conjugated alkoxytrienes in which one of the double bonds is embedded a heterocyclic moiety are obtained by Pd-catalyzed coupling reaction lactam- and lactone-derived vinyl triflates with α-alkoxydienylboronates. These compounds undergo 4π electrocyclization process (Nazarov reaction) under acidic conditions afford cyclopenta-fused heterocycles good yields. As continuation previous study, torquoselectivity this Nazarov has been investigated using 2-alkyl-substituted pyrrolidinone 2-...

Three different procedures are compared to obtain properly substituted divinyl ketones in which one of the double bonds is embedded a five-membered heterocyclic structure and therefore suitable produce cyclopenta-fused pyrrole derivatives by acid-catalyzed Nazarov reaction. These, on treatment with TFA, afforded 2,4-cis-disubstituted 2,3,4,5-tetrahydro-1H-cyclopenta[b]pyrrol-6-ones high stereocontrol. One these products was oxidized corresponding 4,5-dihydro-1H-cyclopenta[b]pyrrol-6-one...

[reaction: see text] A highly efficient carbonylative Suzuki-Miyaura coupling reaction of lactam-derived vinyl triflates and alkenylboronic acids afforded 2-(N-methoxycarbonylamino)-1,4-pentadien-3-ones as suitable substrates for the Nazarov reaction. The most competent Lewis were Cu(OTf)(2) (2 mol %) Sc(OTf)(3) (3 in DCE, which provided products excellent yield. As both subsequent high yielding, overall methodology is a concise route to [1]pyrindine systems.

Density functional theory (DFT) has been used to define the energy profiles of Nazarov reaction involving cyclic systems. The calculations were carried out at B3LYP/6-311G** level and solvent (dichloromethane) contribution was estimated by using recently developed SM5.43R solvation model. DFT first determine associated with electrocyclization reactions 3-hydroxy- 3-ethoxypentadienyl cations in which one double bonds is embedded O-heterocyclic carbocyclic In particular, effects on rate...

The direct transformation of lactam-, lactone-, and thiolactone-derived triflates into N-methoxy-N-methyl or morpholine Weinreb amides has been realized using Pd-catalyzed aminocarbonylation under CO atmospheric pressure at room temperature. carbonylative coupling can be efficiently carried out with 2% catalyst in the presence Xantphos as a ligand. smoothly react nucleophiles to afford acylated aza-, oxa-, thio-heterocycles. proposed methodology could advantageously exploited for synthesis...

Abstract An efficient chemoenzymatic synthesis of both enantiomers fagomine, as well cis and trans ‐4‐hydroxypipecolic acid is reported. The starts from commercial δ‐valerolactam which, after a Pd‐catalyzed methoxycarbonylation the corresponding vinyl phosphate, subjected to allylic oxidation give racemic 4‐hydroxytetrahydropyridine derivative in 57 % overall yield. This product resolved by an enzyme‐catalyzed esterification using immobilized lipases Candida antarctica (Novozym 435)...

Strigolactones (SLs) are a new class of plant hormones whose role has been recently defined in shoot branching, root development and architecture, nodulation. They also active the rhizosphere as signalling molecules communication between plants, AMF (arbuscular mycorrhizal fungi) parasitic weeds. In spite crucial multifaceted biological SLs, current knowledge on SL biosynthetic pathway perception/transduction mechanism is still incomplete. Both genetic molecular approaches required to...

The first total synthesis of the natural product bruceolline I, isolated in small quantities from ethanol extract Brucea mollis stems, was achieved 29% yield over nine steps and with high enantiomeric purity (>98%). key step process is tandem gold-catalyzed rearrangement/Nazarov reaction a propargylic acetate derivative. This provides sufficient amount synthesized I for further bioassays.