Recent developments in asymmetric Heck type cyclization reactions for constructions of complex molecules.

Intramolecular carbometallation-initiated asymmetric transformations are a general and powerful approach for the construction of carbo- and heterocyclic systems with one and more stereocenters. In addition, the newly developed multiple cascade reactions are an attractive strategy for increasing the molecular complexity in one step. In recent years, great progress has been made in this area with the use of various palladium and nickel complexes with P- and N-donor chiral ligands.

Developmental, behavioral and endocrine alterations in male rats at early and late postnatal life following in utero exposure to low dose di--butylphthalate.

Environmental chemical pollutants that interfere with hormonal homeostasis or hormone signaling are the relevant agents inducing congenital or postnatally developed reproductive abnormalities in human beings, wild and domestic animals. In this study, we are examining reproductive effects of prenatal exposure of male rats to a low dose di--butylphthalate (DBP). Wistar female rats were given intragastrically DBP at a daily dose of 100 mg/kg b.

Convenient access to pyrrolidin-3-ylphosphonic acids and tetrahydro-2-pyran-3-ylphosphonates with multiple contiguous stereocenters from nonracemic adducts of a Ni(II)-catalyzed Michael reaction.

A new synthetic strategy toward nonracemic phosphoryl-substituted pyrrolidines and tetrahydropyranes with three and five contiguous stereocenters is presented. Readily available β-keto phosphonates react with conjugated nitroolefins in the presence of a chiral Ni(II) complex to give nitro keto phosphonates with two stereocenters with excellent enantioselectivity and moderate to high diastereoselectivity. These products were used for a reductive cyclization leading to pyrrolidin-3-ylphosphonic acid and for reactions with aldehydes yielding tetrahydropyranylphosphonates as individual stereoisomers.

Synthesis of non-racemic 4-nitro-2-sulfonylbutan-1-ones via Ni(II)-catalyzed asymmetric Michael reaction of β-ketosulfones.

Functionally substituted sulfones with stereogenic centers are valuable reagents in organic synthesis and key motifs in some bioactive compounds. The asymmetric Michael addition of β-ketosulfones to conjugated nitroalkenes in the presence of Ni(II) complexes with various chiral vicinal diamines was studied. This reaction provides convenient access to non-racemic 4-nitro-2-sulfonylbutan-1-ones with two stereocenters with high yield and excellent enantioselectivity (up to 99%).