10.1055/s-0037-1612422
The research aims to develop a new approach for the construction of quaternary stereogenic centers bearing nitrogen substituents in an enantioselective manner. The strategy leverages the [1,3]-chirality transfer from a chiral primary alcohol equivalent through an allyl cyanate-to-isocyanate rearrangement. The efficiency of this approach was demonstrated in the eight-step synthesis of the marine natural product (+)-geranyllinaloisocyanide, achieving an overall yield of 43%. Key chemicals used in the process include chiral primary alcohol equivalent, allyl cyanate, isocyanate, and various reagents such as diethylzinc, trichloroacetyl isocyanate, potassium carbonate, trifluoroacetic anhydride, N,N-diisopropylethylamine, lithium triethylborohydride, and cesium fluoride, among others. The study concluded that the allyl cyanate-to-isocyanate rearrangement with enantiomerically enriched α-silyl allyl alcohol is a highly effective method for chirality transfer, showcasing its potential for further applications in the synthesis of nitrogen-containing natural products.
10.1039/b925209f
This research aims to develop a short and efficient method for synthesizing enantiopure (S)- and (R)-2-arylpyrrolidines with high enantiomeric purity (ee >99%). The study builds on prior work using N-sul?nyl imines for synthesizing N-containing compounds and explores the potential of g-chloro N-(tert-butanesul?nyl)ketimines as precursors for chiral 2-arylpyrrolidines. Key chemicals used include g-chloroketones, (R)- or (S)-tert-butanesul?namide, lithium triethylborohydride (LiBEt3H), sodium borohydride, and potassium hydroxide. The researchers found that reducing (RS)-N-[1-aryl-4-chlorobutylidene]-tert-butanesul?namides with LiBEt3H in tetrahydrofuran at -78°C followed by warming to room temperature yielded (RS,S)-2-aryl-1-(tert-butanesul?nyl)pyrrolidines in high yield. Subsequent acid deprotection with anhydrous HCl in dioxane produced the desired (S)- and (R)-2-arylpyrrolidines. The study concludes that this method provides an efficient route to enantiopure 2-arylpyrrolidines, which are valuable as pharmaceutical subunits and chiral auxiliaries.
10.1006/bioo.1995.1002
The study investigates the design and total convergent synthesis of new analogs of cholecalciferol (vitamin D) with the CD-ring system replaced by a two-carbon aliphatic spacer. The researchers aimed to simplify the structure of vitamin D-based therapeutics by identifying the essential structural parts responsible for its activity. The key chemicals involved include vitamin D derivatives, such as vitamin D3 and 1α-hydroxyvitamin D3, which serve as precursors for the ring fragments. The chain fragment is derived from S-(-)-β-citronellol, a natural monoterpene. The synthesized compounds, RAD and RAD2, are designed as des-CD analogs of 25-OH-D3 and 1,25-(OH)2D3, respectively, with an unnatural configuration at C-20. The study employs various reagents and conditions, such as imidazole, t-BuMe2SiCl, MCPBA, lithium triethylborohydride, and pyridinium chlorochromate, to achieve the desired modifications and coupling of the ring and chain fragments. The results provide insights into the potential for developing more effective therapeutic agents based on the simplified structure of vitamin D.
F; 
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