"PREPARATIONS AND REACTIONS OF RIEKE METALS …

We have also synthesized block copolythiophenes by sequential addition of two organozinc monomers.

Procedure for the Preparation of Highly Reactive Rieke Zinc

Abstract: Addition of selected organo-zinc halides to N-phenylBenzenesulfonimine with a copper catalyst under mild conditions leads to substitutedsulfonamides. Although experimental conditions and workup have not been optimized, bestyields have been obtained when using benzyliczinc halides .

Accordingly, dibromo and/or bromo-iodo compounds were polymerized through the Rieke method.

Preparation of Rieke Zinc 13 3.2 ..

The asymmetric total synthesis of 3-hydroxyleukotriene B4 (3-OH-LTB4), an ethanol-inducible proinflammatory antacoid, was achieved using a triply convergent strategy for the sequential union of propargylic arsonium salt 3 with pyranosides 2a,b and furanose 4. Both saccharide subunits were derived from commercial 2-deoxy-D-ribose. The key transformation involved palladium-mediated coupling of bromoacetylenide 9 with stannylglycal 6a,b. Subsequent Rieke zinc hydrogenation of acetylene 10a,b and controlled ionic reduction of the cross-conjugated cyclic enol ether using NaBH3CN at pH ~ 4-4.5 established the cis-Δ6,7-olefin and C(5)-hydroxyl stereochemistry, respectively, and led to 11a,b. Methyllactol hydrolysis, PCC oxidation, methanolysis, and desilylation afforded 3(R)- and 3(S)-OH-LTB4 methyl esters, respectively. On the basis of chromatographic and mass spectral comparisons, enzymatically derived 3-OH-LTB4 is composed principally of the 3(S)-isomer (≥ 95%).

Rieke zinc is generally prepared by the reduction of zinc chloride with lithium employing a stoichiometric amount of naphthalene.

AB - The asymmetric total synthesis of 3-hydroxyleukotriene B4 (3-OH-LTB4), an ethanol-inducible proinflammatory antacoid, was achieved using a triply convergent strategy for the sequential union of propargylic arsonium salt 3 with pyranosides 2a,b and furanose 4. Both saccharide subunits were derived from commercial 2-deoxy-D-ribose. The key transformation involved palladium-mediated coupling of bromoacetylenide 9 with stannylglycal 6a,b. Subsequent Rieke zinc hydrogenation of acetylene 10a,b and controlled ionic reduction of the cross-conjugated cyclic enol ether using NaBH3CN at pH ~ 4-4.5 established the cis-Δ6,7-olefin and C(5)-hydroxyl stereochemistry, respectively, and led to 11a,b. Methyllactol hydrolysis, PCC oxidation, methanolysis, and desilylation afforded 3(R)- and 3(S)-OH-LTB4 methyl esters, respectively. On the basis of chromatographic and mass spectral comparisons, enzymatically derived 3-OH-LTB4 is composed principally of the 3(S)-isomer (≥ 95%).

Employing the Rieke zinc obtained with this enhanced procedure, several regioregular copolythiophenes were synthesized.


Efficient Synthesis of Functionalized Organozinc …

The reactivity of zinc metal is increased in so-called Rieke zinc obtained by reduction of zinc chloride by potassium metal.

Rieke Metals Inc. - R&D Chemicals

When we started to perform the preparation of Rieke zinc with a new source of naphthalene, the in situ formed zinc particles agglomerated to chunky metal clusters, unlike upon application of the ‘old’ naphthalene source, which gave Rieke zinc as a finely distributed black slurry.

Copper Mediated Addition of Organo-zinc Reagents to …

We offer a unique line of fine organic chemicals for drug discovery. Rieke Metals supplies quantities from grams to kilograms, ensuring high purity and service every step of the way.

Organozinc Compound - Synthesis..

Rieke Metals Inc. (RMI) began in 1991 with it's foundation in over 40 years of research in active metals. Today the company sells active Rieke Zinc and Magnesium, Grignard and Organozinc reagents, fine organic chemicals and organic semi-conducting polymers/monomers including P3HT.

Catalysis and Inorganic Chemistry

Secondly, we believe that this new procedure will definitely increase the application of Rieke zinc in both general organozinc chemistry and functionalized conjugated polymer synthesis as organozinc reagents show excellent chemoselectivity and good functional group tolerance and stability compared to the more reactive Grignard reagents.