Palle Breistein

One‐Pot Three‐Component Catalytic Enantioselective Synthesis of Homoallylboronates

No longer a simple bor(ation): The title reaction between bis(pinacolato)diboron, enals, and 2-(triphenylphosphoranylidene)acetates employing bench-stable copper salts and a simple chiral amine co-catalyst is presented. The reaction proceeds through a catalytic asymmetric conjugate borane addition/Wittig sequence wherein the β-boration step is 1,4-selective and gives the corresponding homoallylboronate products with high enantiomeric ratios.

Direct Regiospecific and Highly Enantioselective Intermolecular α‐Allylic Alkylation of Aldehydes by a Combination of Transition‐Metal and Chiral Amine Catalysts

The first direct intermolecular regiospecific and highly enantioselective α-allylic alkylation of linear aldehydes by a combination of achiral bench-stable Pd(0) complexes and simple chiral amines as co-catalysts is disclosed. The co-catalytic asymmetric chemoselective and regiospecific α-allylic alkylation reaction is linked in tandem with in situ reduction to give the corresponding 2-alkyl alcohols with high enantiomeric ratios (up to 98:2 e.r.; e.r.=enantiomeric ratio). It is also an expeditious entry to valuable 2-alkyl substituted hemiacetals, 2-alkyl-butane-1,4-diols, and amines. The concise co-catalytic asymmetric total syntheses of biologically active natural products (e.g., Arundic acid) are disclosed.

Catalytic enantioselective β -alkylation of α,β-unsaturated aldehydes by combination of transition-metal- and aminocatalysis : Total synthesis of bisabolane sesquiterpenes

Branching out! The first co-catalytic enantioselective (up to 98:2 e.r.) β-alkylation of α,β-unsaturated aldehydes by combination of simple chiral amine and copper catalysts provides β-branched aldehydes in a one-pot protocol. The methodology was applied to the short total syntheses of bisabolane sesquiterpenes (S)-(+)-curcumene, (E)-(S)-(+)-3-dehydrocurcumene and (S)-(+)-tumerone.

One-pot three-component highly selective synthesis of homoallylboronates by using metal-free catalysis.

One-Pot Three-Component Highly Selective Synthesis of Homoallylboronates by Using Metal-Free Catalysis

Chemical ecology and insect conservation: optimising pheromone-based monitoring of the threatened saproxylic click beetle Elater ferrugineus

Elater ferrugineus is a saproxylic click beetle inhabiting old deciduous trees in Europe. It is threatened throughout its area of distribution due to habitat loss. No efficient monitoring method has been available for this species, but observed attraction of females to (R)-(+)-γ-decalactone, which is a male-produced sex pheromone of its prey, the scarab beetle Osmoderma eremita, has led to the development of an odour lure for monitoring. In addition, four esters have recently been identified from the pheromone-producing gland in female E. ferrugineus, and a blend of these esters is highly attractive to conspecific males in the field, revealing an alternative odour-based method for monitoring this species. However, no rigorous analysis has been performed to check whether all four esters show biological activity in male E. ferrugineus, and whether its own sex pheromone is a more potent lure than the prey kairomone for monitoring of E. ferrugineus. In this study, we reinvestigated the E. ferrugineus sex pheromone, using electrophysiological and behavioural analyses, and found that only one of the esters, 7-methyloctyl (Z)-4-decenoate, is active. In addition, trapping experiments revealed that 7-methyloctyl (Z)-4-decenoate is a much more efficient attractant for male E. ferrugineus than the prey pheromone is for conspecific females, or any sex of O. eremita. With a very efficient odour lure at hand, novel information about current distribution, local population sizes, and dispersal ranges in E. ferrugineus can now be obtained, which can aid in conservation efforts to protect this threatened insect and its habitat.