Publications by authors named "Jun-Cheng Zheng"
Regioselectivity of alkylidene carbene-mediated C-H insertion was explored utilizing electronic, conformational, steric, and stereoelectronic effects. Relying on these factors, highly regio- and chemoselective carbene insertion reaction of C-H bonds in different environments could be obtained. The observed selectivity clearly indicates that an electronic effect plays a more important role than steric effect.
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- A new reaction method has been created that uses pyridine as a catalyst to form dihydrofurans and dihydropyrroles.
- This process involves α-ylidene-β-diketones and α,β-unsaturated imines reacting with diazoacetates.
- The results show yields as high as 96% and good control over the product's stereochemistry.
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- Researchers developed an efficient method to create optically active cyclohexadiene epoxides and vinylcyclopropanes using camphor-derived sulfur ylide.
- This process involves reactions with alpha,beta-unsaturated ketones, leading to high selectivity and impressive yields.
- The resulting compounds demonstrate excellent diastereoselectivity and moderate to high enantioselectivity, making them valuable in organic synthesis.
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- Scientists have created a new way to make special chemicals called cis-trisubstituted vinylaziridines, which are used in medicine and chemistry.
- This new method combines two steps done together: one involves a reaction with sulfur to create a ring structure, and the other uses a metal called palladium to change the structure slightly.
- This process is really good at making the desired result, which means they are likely to get the right chemical every time they try it!
A systematic study of C-H insertion reactions with variously substituted and conformationally constrained substrates was carried out. High selectivity in the insertion between two competing C-H bonds caused by a strong stereoelectronic effect of an oxygen substituent was achieved. This regioselective C-H insertion reaction was employed as a platform to develop a concise asymmetric synthesis of platensimycin.
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- Researchers developed a method to create optically active dihydrofurans using a reaction involving camphor-derived sulfur ylide.
- The process is highly efficient, meaning it works well in producing the desired compound without wasting resources.
- The selectivity of the synthesis indicates that the method reliably produces a specific type of dihydrofuran, which is important for achieving the desired chemical properties.
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- A method has been created using cinchonidine (or cinchonine) ammonium salts to react with nitroolefins.
- This process takes place in the presence of Cs2CO3.
- The result is the production of optically active isoxazoline N-oxides with high enantiomeric excess (ee) and good diastereomeric values (de).
[reaction: see text] Optically active cis-2-substituted vinylaziridines are synthesized by the reaction of N-tert-butylsulfinylimines with telluronium ylides with excellent diastereoselectivity in good to excellent yields.
View Article and Find Full Text PDFThe Michael addition-elimination of ylide to alpha,beta-unsaturated imines leads to a highly diastereoselective and enantioselective synthesis of vinylcyclopropanecarbaldehydes in good to high yields for the first time. A sequential cyclopropanation-aziridination protocol for the preparation of cyclopropylaziridines is also developed with good diastereoselectivity in good to high yields.
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