Flexible interactions of the rare-earth elements Y, La, and Lu with phosphorus in metallacyclohexane rings.

A geometrically flexible bifunctional (bis)aminophosphine ligand was synthesized in a three-component, one-pot Kabachnik-Fields reaction using butylphosphine, paraformaldehyde, and 3,5-dimethyl aniline. The product, bis((3,5-dimethylphenyl)aminomethyl) butylphosphine (BiAMP ), containing two secondary amines and a tertiary phosphine, was isolated in good yields. Deprotonation of both N-H groups with (trimethylsilyl)methylpotassium (K-CHSiMe), followed by salt metathesis with LaI, YI, and LuI generated the corresponding MI(BiAMP )(thf) complexes (M = Y (1), La (2), and Lu (3)) in good yields.

Enantioselective allylic alkylation of stereodefined polysubstituted copper enolates as an entry to acyclic quaternary carbon stereocentres.

A sequence of regio- and stereoselective carbometalation followed by oxidation of ynamides leads to stereodefined fully substituted enolates that subsequently react with various functionalized allyl bromide reagents to provide the expected products possessing an enantiomerically pure quaternary carbon stereocentre in the α-position to the carbonyl group in excellent yields and enantiomeric ratios after cleavage of the oxazolidinone moiety. Three new bonds are formed in a single-pot operation.

Stereodefined acyclic trisubstituted metal enolates towards the asymmetric formation of quaternary carbon stereocentres.

Reactions that involve metal enolate species are amongst the most versatile carbon-carbon bond forming processes available to synthetic chemists. Enolate species are involved in a multitude of powerful applications in asymmetric organic synthesis, but the generation of fully substituted enolates in a geometrically defined form is not easily achieved especially in acyclic systems. In this Feature Article we focus on the most prominent examples reported in the literature describing the formation of highly diastereo- and enantiomerically enriched quaternary stereocentres in acyclic molecules derived from stereodefined non-cyclic trisubstituted metal enolates.

All-carbon quaternary stereogenic centers in acyclic systems through the creation of several C-C bonds per chemical step.

In the past few decades, it has become clear that asymmetric catalysis is one of the most powerful methods for the construction of carbon-carbon as well as carbon-heteroatom bonds in a stereoselective manner. However, when structural complexity increases (i.e.

Oxenoids in organic synthesis.

Experimental and theoretical studies of metalated peroxides confirmed their unique properties as oxenoids (electrophilic oxidants) allowing for a highly selective and efficient oxidation processes of nucleophilic organometallic species. In this short review we present the most prominent examples of the application of this class of reagents towards organic synthesis.

Regio- and stereoselective carbometallation reactions of N-alkynylamides and sulfonamides.

The carbocupration reactions of heterosubstituted alkynes allow the regio- and stereoselective formation of vinyl organometallic species. N-Alkynylamides (ynamides) are particularly useful substrates for the highly regioselective carbocupration reaction, as they lead to the stereodefined formation of vinylcopper species geminated to the amide moiety. The latter species are involved in numerous synthetically useful transformations leading to valuable building blocks in organic synthesis.

Stereodefined trisubstituted enolates as a unique entry to all-carbon quaternary stereogenic centers in acyclic systems.

This protocol describes a new approach for the preparation of stereodefined trisubstituted chiral enolate species, avoiding conventional asymmetric enolization of carbonyl compounds. This protocol was developed as a single-flask synthetic sequence and therefore does not require isolation or purification of intermediate compounds. The sequence starts from a regioselective carbocupration reaction of readily accessible chiral ynamides; this is followed by oxidation of the generated vinylcuprate with a commonly available oxidizing reagent (tert-butyl hydroperoxide) in order to generate an enolate that completely retains its configuration.

Forming all-carbon quaternary stereogenic centres in acyclic systems from alkynes.

The formation of all-carbon quaternary stereocentres in acyclic systems is one of the most difficult contemporary challenges in modern synthetic organic chemistry. Particularly challenging is the preparation of all-carbon quaternary stereocentres in aldol adducts; this difficulty is problematic because the aldol reaction represents one of the most valuable chemical transformations in organic synthesis. The main problem that limits the formation of these stereocentres is the absence of an efficient method of preparing stereodefined trisubstituted enolates in acyclic systems.