boron and allyl-alcohol

Chiral secondary allylboronates are obtained in high enantioselectivities and 1,6:1,4 ratios by the copper-catalyzed 1,6-boration of electron-deficient dienes with bis(pinacolato)diboron (B2(pin)2). The reactions proceed efficiently using catalyst loadings as low as 0.0049 mol %. The allylboronates may be oxidized to the allylic alcohols, and can be used in stereoselective aldehyde allylborations. This process was applied to a concise synthesis of atorvastatin, in which the key 1,6-boration was performed using only a 0.02 mol % catalyst loading.

Topics: Boron; Catalysis; Copper; Molecular Structure; Propanols; Stereoisomerism

We have developed a polymer-incarcerated bimetallic Au-Pd nanocluster and boron as a catalyst for the sequential oxidation-addition reaction of 1,3-dicarbonyl compounds with allylic alcohols. The desired tandem reaction products were obtained in good to excellent yields under mild conditions with broad substrate scope. In the course of our studies, we discovered that the excess reducing agent, sodium borohydride, reacts with the polymer backbone to generate an immobilized tetravalent boron catalyst for the Michael reaction. In addition, we found bimetallic Au-Pd nanoclusters to be particularly effective for the aerobic oxidation of allylic alcohols under base- and water-free conditions. The ability to conduct the reaction under relatively neutral and anhydrous conditions proved to be key in maintaining good catalyst activity during recovery and reuse of the catalyst. Structural characterization (STEM, EDS, SEM, and N(2) absorption/desorption isotherm) of the newly prepared PI/CB-Au/Pd/B was performed and compared to PI/CB-Au/Pd. We found that while boron was important for the Michael addition reaction, it was found to alter the structural profile of the polymer-carbon black composite material to negatively affect the allylic oxidation reaction.

Topics: Boron; Carbon; Catalysis; Gold; Molecular Structure; Nanostructures; Oxidation-Reduction; Palladium; Polymers; Propanols

All-ene one! Three out of four stereoisomers of 2-vinyl-1,3-diols can be obtained from a single allene. A simple variation of the reaction conditions modifies the stereochemical outcome of the addition of an allene to an aldehyde via hydroboration. Stereocontrol is dependent upon the order in which the reagents are mixed (leading to E or Z boron species) and the type of aldehyde (aliphatic or aromatic) used.

Topics: Aldehydes; Alkadienes; Boron; Propanols; Stereoisomerism

The nickel-catalyzed reaction of carbonyls and dienes was accomplished in a regio- and stereoselective fashion employing a stoichiometric amount of bis(pinacolato)diboron. This reductive coupling furnishes an allyl boronic ester as the reaction product, a compound which was readily converted to the derived allylic alcohol by oxidative workup.

Topics: Aldehydes; Boron; Catalysis; Molecular Structure; Nickel; Propanols; Stereoisomerism