Search

A biomimetic iodofunctionalization of aromatic and heteroaromatic compounds has been developed using NaI as a source of iodine and 30% H2O2 as a mild oxidant, as well as SeCl4 as a commercially available catalyst in water without a co-solvent. The method affords iodinated compounds in isolated yields of 37 to 99%. The catalytic system has potential for the bromination of aromatic substrates.

In the present work we developed a practical, faster, and more sustainable way to prepare conjugated materials, derived from poly-p-phenylenes (PPPs), using 10% palladium on carbon as catalyst and distilled water as solvent under microwave heating for 3 h. The oligomers were also prepared by the classical Suzuki reaction to enable a comparison of results. All materials were characterized by nuclear magnetic resonance (NMR), infrared (IR), absorption and emission analysis, gel permeation chromatography (GPC), and thermogravimetric analysis. The polymers prepared by the alternative method were obtained in higher yields than the polymers produced by the classical Suzuki reaction. In addition, characterization data showed no significant differences in terms of molecular structures and luminescent properties between the polymers synthesized through the different protocols. Therefore, the alternative method developed was considered appropriated for the synthesis of PPPs derivatives.

Convergent total synthesis of (±)-apomorphine hydrochloride was accomplished by an approach that employs in the key step a sequence of transformations involving a [4+2]-cycloaddition reaction followed by a hydrogen migration. Through this sequence of transformations, the desired aporphine core was obtained regioselectively in 75% isolated yield. Since only one regioisomer was produced in the key step of the synthesis, a polar [4+2]-cycloaddition mechanism was proposed. Furthermore, NMR experiments and theoretical calculations were carried out to elucidate the hydrogen migration mechanism. (±)-Apomorphine hydrochloride was achieved after 9 steps in an overall yield of 8% involving benzyne chemistry.

A modular approach for the synthesis of functionalized silylbiaryl triflates has been developed. Iodinated silylaryl triflates were prepared via a gram-scale diiodination reaction, followed by a one-flask transformation, in 42–52% overall yield. The iodinated silylaryl triflates were subjected to a novel chemoselective Suzuki reaction with arylboronic acids, using PdCl2(PPh3)2 as catalyst and K2CO3 as base in THF/H2O (1:1) at 80 °C for 24 hours, which afforded silylbiaryl triflates in 47–81% yield.

Z-Vinylic tellurides react with metal acetylides under nickel complexes catalysis to give Z-enynes and Z-enediynes in good yields.

The coupling reaction between 2,6-diiodoanisoles and terminal alkynes using Pd(PPh3)2Cl2 and CuI as catalysts and diisopropylamine as base in toluene at room temperature for 12 h produced selectively alkynylated 2-iodoanisoles, in good to excellent yields (52-95%), which are useful building blocks with potential application in the synthesis of functionalized benzo[b]furans. A reação de acoplamento entre 2,6-diiodoanisóis e alcinos terminais usando Pd(PPh3)2Cl2 e CuI como catalisadores e diisopropilamina como base em tolueno a temperatura ambiente por 12 h produziu seletivamente 2-iodoanisóis aquinilados, em rendimentos de bons a excelentes (52-95%), os quais são blocos de construção úteis com potencial aplicação na síntese de benzo[b]furanos funcionalizados.

The cross-coupling reaction between aryl halides and terminal alkynes catalyzed by palladium complexes and copper (I) salts can be considered an useful synthetic tool in the C(sp 2 )-C(sp) bond formation leading to disubstituted acetylenic compounds. 1 Accordingly, in this work we present our preliminary results involving the selective coupling reaction between 2,6-diiodoanisoles and terminal alkynes catalyzed by palladium and copper, in order to produce disubstituted alkynes bearing a functionalized aromatic ring.

Notable features of the diaryl ether synthesis include no need for transition metal catalysts and tolerance of halide substituents.

The kinetic resolution of (±)-iodophenylethanols was carried out using lipase from Candida antarctica and in some cases the enantiomeric excesses were high (up to >98%). Enantiomerically enriched (S)-iodophenylethanols produced by the enzymatic resolution process were used in the synthesis of chiral biphenyl compounds by the Suzuki reaction with good yields (63–65%).

tert -Butyldimethylsilyl ethers of propargylic alcohols are hydrotellurated regioselectively to give 1,2- Z -vinylic tellurides. Enantiomerically pure propargylic alcohols give enantiomerically pure vinylic tellurides, which are coupled with alkynes under Pd catalysis to give enantiomerically pure allylic enynols.

A number of chiral propargylic and allylic alcohols were resolved by lipase-catalyzed kinetic resolution (Novozyme 435). In some cases the enantiomeric excess was high (up to >99%).

Under palladium dichloride catalysis, vinylic tellurides couple efficiently with alkynes with retention of the double-bond geometry. Herein we show that the amount of the PdCl2 catalyst can be redu...