Asymmetric synthesis of ferrocenylazido alcohols and their derivatization to novel chiral ferrocenyl-thiazoline ligands with C2-symmetry

2-Thiazolines: an update on synthetic methods and catalysis

2-Thiazolines are important building blocks in organic synthesis and are of great importance in many areas of chemistry. At the end of the last century, the use of 2-thiazolines increased in a significant way, especially in synthesis and catalysis. This review highlights the synthetic and catalytic value of 2-thiazolines in the last two decades. We will discuss the new synthetic methodologies for obtaining these heterocycles including new schemes for accessing their asymmetric versions. Most of the new catalytic applications include a variety of 2-thiazoline ligands containing diverse donor atoms, which in combination with metals like Pd, Ir, and Cu, among others, exhibit remarkable catalytic performances.

Chiral bidentate [N,S]-ferrocene ligands based on a thiazoline framework. Synthesis and use in palladium-catalyzed asymmetric allylic alkylation

New chiral 1,2-disubstituted ferrocenyl ligands were synthesized using (S)-4-methyl-2-thiazoline as DMG. Their ability to act in Pd-catalyzed AAA has been demonstrated.

Asymmetric synthesis of 2,4,5-trisubstituted Δ2-thiazolines

Δ²-Thiazolines are interesting heterocycles that display a wide variety of biological characteristics. They are also common in chiral ligands used for asymmetric syntheses and as synthetic intermediates. Herein, we present asymmetric routes to 2,4,5-trisubstituted Δ²-thiazolines. These Δ²-thiazolines were synthesized from readily accessible/commercially available α,β-unsaturated methyl esters through a Sharpless asymmetric dihydroxylation and an O→N acyl migration reaction as key steps. The final products were obtained in good yields with up to 97% enantiomeric excess.

Electron ionisation mass spectral studies of bridgehead-fused Delta2-norbornanethiazolines

The electron ionisation (EI) mass spectra of a series of bridgehead-fused Delta2-norbornanethiazolines, a new class of bridgehead-norbornane derivatives, have been studied and their cleavage mechanisms rationalised on the basis of the substituent shifts as well as on the identification of relevant peaks through accurate mass measurements and collision-induced dissociation tandem mass spectrometric experiments. The fragmentation patterns of isomeric pairs of 6,6- and 10,10-dimethylnorbornanethiazolines are almost identical, probably due to an initial isomerisation of molecular ion previous to the fragmentation. In general, the dominant peaks in the spectra of all the studied compounds originate from initial alpha-cleavages of C(5)-C(6) or C(1)-C(10) bonds, followed by concomitant homolytic cleavage of C(1)-C(9) and C(7)-C(10) bonds. The driving force for this fragmentation pathway, directed by the gem-dimethyl group, is the formation of a highly stabilised thiazolilmethyl cation which constitutes the base peak in all the spectra and allows the identification of these interesting ligands.

Stereoselective Michael Addition of Carbon-, Nitrogen-, Oxygen-, and Sulfur-Centered Nucleophiles on Enantiopure Hydroxylated 6,7-Dehydro-5-oxoindolizidine. Synthesis of Carbon- or Hetero-7-Substituted Swainsonine Analogues

Enantiopure alpha,beta-unsaturated delta-lactams 1 and 2 react stereoselectively with carbon-, nitrogen-, sulfur-, and oxygen-centered nucleophiles. The synthetic potential of these conjugate additions is demonstrated through the synthesis of two new substituted indolizidines: (7R)-7-amino-8-deoxyswainsonine 3 and (7R)-7-acetylaminoswainsonine 4.