Cobalt-catalyzed reductive Mannich reactions of 4-acryloylmorpholine with N-tosyl aldimines.

Using cobalt catalysis, diethylzinc promotes the conjugate reduction of 4-acryloylmorpholine to produce the corresponding ethylzinc enolate, which reacts with N-tosyl aldimines to afford beta-aminoamides.

Diastereoselective cobalt-catalyzed reductive aldol cyclizations using diethylzinc as the stoichiometric reductant.

[reaction: see text] Cobalt catalysis enables a new method for the generation of zinc enolates using diethylzinc to reduce alpha,beta-unsaturated amides. This method has been applied to a high-yielding diastereoselective reductive aldol cyclization.

trans-1-Sulfonylamino-2-isoborneolsulfonylaminocyclohexane derivatives: excellent chiral ligands for the catalytic enantioselective addition of organozinc reagents to ketones.

The catalytic enantioselective addition of different organozinc reagents (such as alkyl and aryl derivatives or in situ generated aryl, allyl alkenyl, and alkynyl derivatives obtained through different transmetallation processes) to simple ketones has been accomplished by using titanium tetraisopropoxide and chiral ligands derived from substituted trans-1-sulfonylamino-2-isoborneolsulfonylaminocyclohexane, producing the corresponding tertiary alcohols with enantiomeric excesses (ee) up to >99 %. A simple and efficient procedure for the synthesis of the chiral ligands used in these reactions is described.

Highly enantioselective copper(I)-phosphoramidite-catalysed additions of organoaluminium reagents to enones.

Simple phosphoramidite ligands afford good to excellent levels of enantioselectivity in 1,4-additions of AlR3 species to enones; sequential carboalumination-ACA cascades are possible.

Computation of the disk of least confusion for conic mirrors.

We use geometrical optics to compute, in an exact way and by using the third-order approximation, the disk of least confusion (DLC) or the best image produced by a conic reflector when the point source is located at any position on the optical axis. In the approximate case we obtain analytical formulas to compute the DLC. Furthermore, we apply our equations to particular examples to compare the exact and approximate results.