Diego dos Santos Pisoni

Symmetrical and Asymmetrical Cyanine Dyes. Synthesis, Spectral Properties, and BSA Association Study

New cyanines were prepared by an efficient and practical route with satisfactory overall yield from low-cost starting materials. The photophysical behavior of the cyanines was investigated using UV-vis and steady-state fluorescence in solution, as well as their association with bovine serum albumin (BSA) in phosphate buffer solution (PBS). No cyanine aggregation was observed in organic solvents or in phosphate buffer solution. The alkyl chain length in the quaternized nitrogen was shown to be fundamental for BSA detection in PBS in these dyes.

Synthesis and AChE inhibitory activity of new chiral tetrahydroacridine analogues from terpenic cyclanones

This work describes the enantioselective synthesis of a new series of terpenic chiral 9-aminotetrahydroacridine analogues. Several chiral ketones were synthesized from natural monoterpenes in an optically active form and subjected to the cyclodehydration reactions with anthranilonitrile in the presence of BF(3).Et(2)O as catalyst. The 9-aminotetrahydroacridine analogues were tested as acetylcholinesterase (AChE) inhibitors. Based on qualitative structure-activity relationship some trends are suggested.

Lewis acid promoted Friedländer condensation reactions between anthranilonitrile and ketones for the synthesis of tacrine and its analogues

The scope of Lewis acid-promoted cyclodehydratation reactions between anthranilonitrile and several ketones, to afford tacrine and its derivatives, was expanded to include the use of various metal chloride salts not reported in the literature. The ability of the Lewis acids to effectively promote the cyclodehydratation between anthranilonitrile and cyclohexanone as the ketone was found to be the following order: InCl3 > AlCl3 ~ BF3.Et2O > FeCl3 > BiCl3 ~ SbCl3 ~ SnCl2.2H2O. The reactions were performed under both solvent and solvent-free conditions in good to excellent yields. Other Lewis acids screened, such as RuCl3, CeCl3, NiCl2, CoCl2.2H2O and CsCl were not effective.

InCl3/NaClO: a reagent for allylic chlorination of terminal olefins

Tricloreto de indio na presenca de hipoclorito de sodio promove a cloracao alilica de olefinas terminais em meio bifasico (diclorometano/agua) com bons rendimentos. Para estabelecer um procedimento geral, escolheu-se a carvona como composto modelo e otimizou-se a estequiometria, temperatura, e tempo de conversao para o respectivo cloreto alilico. Tratando-se b-pineno com tricloreto de indio/hipoclorito de sodio obteve-se seletivamente o cloreto perilico, um precursor importante para a obtencao de derivados de limoneno oxigenados no carbono C-7.

Preparation of (5R)-4,8-dimethylbicyclo[3.3.0]oct-1(8),3-dien-2-one from (-)-limonene oxide: a novel intermediate to the synthesis of 4-5-5 fused tricarbocyclic core present in terpenic natural products

Este trabalho refere-se a sintese enantiosseletiva da dienona (5R)-4,8-dimethylbicyclo[3.3.0]oct1(8),3-dien-2-one. Este intermediario, pode ser reconhecido como um bloco de construcao versatil para a sintese de uma grande variedade de compostos com esqueleto biciclo[3.3.0]octano. A estrategia sintetica empregada aqui faz uso da reatividade invertida de um precursor cianoidrina TMS-eter, como equivalente de ânion acila, para promover uma reacao de alquilacao intramolecular. A sintese formal do (-)-kelsoeno foi realizada pela preparacao do intermediario avancado (1R,5S,8R)-4,8dimethylbicyclo[3.3.0]oct-3-en-2-one, a partir da hidrogenacao seletiva do composto intitulado (5R)4,8-dimethylbicyclo[3.3.0]oct-1(8),3-dien-2-one. This paper describes the conversion of the readily available (-)-limonene oxide to the new (5R)4,8-dimethylbicyclo[3.3.0]oct-1(8),3-dien-2-one. This compound holds the prospect of serving as a useful chiral building block or intermediate to prepare a variety of compounds having a bicyclo[3.3.0]octane framework. The synthetic strategy made use of the umpolung reactivity of cyanohydrin TMS ether, as an acyl anion equivalent, in order to promote intramolecular alkylation. The formal synthesis of (-)-kelsoene was achieved by preparing a known advanced intermediate (1R,5S,8R)-4,8-dimethylbicyclo[3.3.0]oct-3-en-2-one via selective hydrogenation of the named compound (5R)-4,8-dimethylbicyclo[3.3.0]oct-1(8),3-dien-2-one.

Enantioselective synthesis of (R)-isocarvone from (S)-perillaldehyde

This work describes the enantioselective preparation of (R)-(+)-isocarvone, (S)-(-)-5-isopropenylcyclohex-2-enone and (S)-(-)-3-isopropenylcyclohexanone starting from (S)-(-)-perillaldehyde. These compounds hold the prospect of serving as useful chiral building blocks or intermediates in organic synthesis.

Synthesis of cyanine dyes: potential fluorescent probes for biological applications

Symmetrical cyanine 6 was synthesized as shown in Scheme 1. The acid-catalysed condensation of 1,1,3,3-tetramethoxypropane (1) with aniline (2) afforded the polymethine precursor 3. Subsequent alkylation of 2,3,3-trimethylindolenine (4) with excess of 1-iodooctane led to the ammonium salt 5 in 75% yield. Next, the condensation reaction of polymethine 3 (1.0 equiv.) with 3H-indolium salt 5 (2.0 equiv.), under reflux in EtOH in the presence of AcONa, afforded the symmetrical cyanine dye 6 in 54% yield.