29304-40-3Relevant academic research and scientific papers
Asymmetric Aza-Wacker-Type Cyclization of N-Ts Hydrazine-Tethered Tetrasubstituted Olefins: Synthesis of Pyrazolines Bearing One Quaternary or Two Vicinal Stereocenters
Kou, Xuezhen,Shao, Qihang,Ye, Chenghao,Yang, Guoqiang,Zhang, Wanbin
supporting information, p. 7587 - 7597 (2018/06/04)
We have developed an asymmetric aza-Wacker-type cyclization of N-Ts hydrazine-tethered tetrasubstituted olefins, affording optically active pyrazolines bearing chiral tetrasubstituted carbon stereocenters. This reaction is tolerant to a broad range of substrates under mild reaction conditions, giving the desired chiral products with high enantioselectivities. Generation of two vicinal stereocenters on the C=C double bonds was also achieved with high selectivities, a process which has been rarely studied for Wacker-type reactions. A mechanistic study revealed that this aza-Wacker-type cyclization undergoes a syn-aminopalladation process. It was also found that for substrates bearing two linear alkyl substituents on the outer carbon atom of the olefin, both of which are larger than a methyl group, the alkyl substituent that is cis to the intranucleophilic group participates more readily in β-hydride elimination. When one of the two alkyl substituents on the outer carbon atom of the olefin is a methyl group, β-hydride elimination proceeds selectively at the methylene side, thus both diastereomers can be prepared via switching the configuration of the olefin. Furthermore, the product can be converted to a pharmaceutical compound in high yields over three steps.
A double Mannich approach to the synthesis of substituted piperidones - Application to the synthesis of substituted E-ring analogues of methyllycaconitine
Chan, Yinman,Balle, Jared,Kevin Sparrow,Boyd, Peter D.W.,Brimble, Margaret A.,Barker, David
experimental part, p. 7179 - 7191 (2010/10/01)
The double Mannich reaction of acyclic α,γ-substituted β-keto esters and bis(aminol) ethers gives substituted 3,5-substituted-4- piperidones with high levels of diastereoselectivity. These piperdiones can be easily transformed into substituted E-ring analogues of the delphinium alkaloid methyllycacotine.
Cytotoxic agents and methods of use
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Page/Page column 22, (2010/02/14)
Disclosed are compounds that inhibit proteasomic activity in cells. Also disclosed are pharmaceutical compositions comprising such compounds as well as methods to treat conditions, particularly cell proliferative conditions, such as cancer and inflammator
A new efficient synthesis of α-methyl-β-ketoesters through an Eschenmoser sulfide reaction
Bellec, Christian,Gaurat, Olivier
, p. 1289 - 1293 (2007/10/03)
Various α-methyl-β-ketoesters were readily synthesized through Eschenmoser condensation of thioamides with a commercially available bromoester. β-Enaminoesters were easily prepared through this sulfide contraction reaction and were hydrolysed to afford the corresponding β-ketoesters in moderate to good yields.
Total synthesis of phenoxan and a related pyrone derivative
Ishibashi, Yasuharu,Ohba, Shigeru,Nishiyama, Shigeru,Yamamura, Shosuke
, p. 2997 - 3000 (2007/10/03)
Phenoxan, HIV-1 inhibitor isolated from the myxobacteria, has been synthesized in 16 steps starting from ethyl 2-methylacetoacetate. The related isomer corresponding to the oxazole part was also obtained via an orthoester-enediol rearrangement.
Sulfur-Extrusive Rearrangement of α-Acylthio Ester by Lithium Amide
Tsuzuki, Kazuo,Akeyoshi, Masaharu,Omura, Satoshi
, p. 395 - 396 (2007/10/02)
α-Acylthio esters readily undergo facile rearrangement to give β-keto esters on treatment with lithium amide at -78 deg C.Thiolactone 3, a key intermediate for thiolactonic antibiotics, was synthesized by utilizing the rearrangement.
