10.3762/bjoc.8.81
The research focuses on the synthesis and coordination behavior of axially chiral oxazoline-carbene ligands with an N-naphthyl framework, specifically their interaction with AuCl·SMe2 to form Au(I) complexes. The main reactants used in the synthesis include methyl 1-hydroxy-2-naphthoate, trifluoromethylation reagents, 2-nitroaniline, Pd/C for reduction, triethyl orthoformate, TsOH for cyclization, and (S)-2-amino-2-phenylethanol, among others. The synthesis process involved several steps, including trifluoromethylation, coupling reactions, reduction, cyclization, and amide formation, leading to the formation of axially chiral ligands. The coordination study with AuCl·SMe2 was conducted using NaOAc in acetonitrile, and the Au(I) complexes were isolated by flash column chromatography. The analysis of the complexes was performed using 1H NMR spectroscopy to compare the chemical shifts of protons on the oxazoline ring before and after complexation, and single-crystal X-ray diffraction studies were employed to confirm the structure of the complexes, revealing a nearly linear coordination geometry around the gold(I) center. The study found that the geometry of the chiral N-naphthyl axis significantly influenced the yields of the Au(I) complexes, with (Sa,S)-7 yielding higher complex yields than (Ra,S)-7.
10.1016/S0040-4039(00)00580-3
The study presents a synthetic approach to (?)-β-conhydrine and its analogues, utilizing N-Boc-2-acyl oxazolidine methodology and ring-closing metathesis (RCM). The process involves a stereoselective reduction of an N-Boc-2-acyl oxazolidine and an RCM on enantiopure trans-3,4,5-trisubstituted oxazolidin-2-ones to create unsaturated bicyclic oxazolidin-2-ones with different ring sizes. One of the bicyclic compounds synthesized was converted into (?)β-conhydrin, and both an unsaturated and a dihydroxylated analogue of this alkaloid were also prepared from the same starting material. The synthesis strategy offers a new pathway for the production of hydroxylated piperidinic alkaloids, with potential applications in the development of biologically active compounds.
10.1055/s-0028-1087672
The research focuses on the development of a flexible and highly regio- and diastereoselective approach to synthesize methyl 5-alkyltetramate derivatives, which are key frameworks in numerous bioactive natural products. The method involves regioselective Grignard reagent additions to 3-methoxymaleimides, followed by diastereoselective reductive dehydroxylation of the resulting N,O-acetals. The experiments utilized various Grignard reagents, such as methyl magnesium iodide and n-butyllithium, and reagents like boron trifluoride etherate and triethylsilane for the reductive dehydroxylation step. The study also explored the use of (S)-phenylglycinol as a chiral auxiliary in the synthesis. The analyses included monitoring the reactions, determining the yields and diastereoselectivities of the products, and characterizing the structures of the synthesized compounds using techniques like X-ray diffraction analysis for compound 29h. The research resulted in the synthesis of various methyl (5S)-5-alkyltetramate derivatives that are otherwise inaccessible by conventional methods based on α-amino acids.
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