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All total 14 Articles be found
All total 14 Articles be foundStereoselective Oxidative Cyclization ofN-Allyl Benzamides to Oxaz(ol)ines
Abazid, Ayham H.,Hollwedel, Tom-Niklas,Nachtsheim, Boris J.
supporting information, p. 5076 - 5080 (2021/07/19)
This study presents an enantioselective oxidative cyclization ofN-allyl carboxamides via a chiral triazole-substituted iodoarene catalyst. The method allows the synthesis of highly enantioenriched oxazolines and oxazines, with yields of up to 94% and enantioselectivities of up to 98% ee. Quaternary stereocenters can be constructed and, besidesN-allyl amides, the corresponding thioamides and imideamides are well tolerated as substrates, giving rise to a plethora of chiral 5-memberedN-heterocycles. By applying a multitude of further functionalizations, we finally demonstrate the high value of the observed chiral heterocycles as strategic intermediates for the synthesis of other enantioenriched target structures.
Diversity oriented concise asymmetric synthesis of azasugars: A facile access to l-2,3-trans-3,4-cis-dihydroxyproline and (3S,5S)-3,4,5-trihydroxypiperidine
Gajare, Vikas S.,Khobare, Sandip R.,Datrika, Rajender,Reddy, K. Srinivas,Rajana, Nagaraju,Kumar, Sarvesh,Venkateswara Rao,Syam Kumar
supporting information, p. 6659 - 6663 (2016/01/28)
Diversity oriented concise asymmetric syntheses of l-2,3-trans-3,4-cis-dihydroxyproline and (3S,5S)-3,4,5-trihydroxypiperidine have been developed from (R)-glycidol. The key step of the synthesis is Sharpless asymmetric dihydroxylation on enantiomerically pure TBDMS protected allylic alcohol 14 which generates the triol intermediate 15 in excellent de. The (2R,3R,4S)-2,3-dihydroxypentanoate derivative 15 was subsequently converted to natural pyrrolidine azasugar 1 and non-natural piperidine azasugar 4 under cascade reaction conditions in good yields.
Synthesis and properties of crosslinked chiral nanoparticles via RAFT miniemulsion polymerization
Xu, Wenliang,Cheng, Zhenping,Zhang, Lifen,Zhang, Zhengbiao,Zhu, Jian,Zhou, Nianchen,Zhu, Xiulin
experimental part, p. 1324 - 1331 (2011/02/26)
Crosslinked chiral nanoparticles were successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) miniemulsion polymerization of 6-O-p-vinylbenzyl-1,2:3,4di-O-isopropylidene-D-galactopyranose (VBPG) using linear poly(VBPG) as the macro-RAFT agent. The polymerization of VBPG in the absence of crosslinker was first studied and the kinetic results showed that the molecular weights of the obtained poly(VBPG) increased linearly with the monomer conversion and was in good consistency with the corresponding theoretical ones while there remained a relative narrow polydisperslty. The effect of the amount of crosslinker, divlnylbenzene, on the nanoparticle size and chiral separation properties of the obtained nanoparticles were investigated in detail using four racemates ±-3-Amino-1,2propanediol, D,L-arablnose, D,L-tartaric acid, and D,L-mandelic acid.
