4136-22-5Relevant articles and documents
Selective Monoacylation of Diols and Asymmetric Desymmetrization of Dialkyl meso-Tartrates Using 2-Pyridyl Esters as Acylating Agents and Metal Carboxylates as Catalysts
Hashimoto, Yuki,Michimuko, Chiaki,Yamaguchi, Koki,Nakajima, Makoto,Sugiura, Masaharu
, p. 9313 - 9321 (2019/08/12)
With 2-pyridyl benzoates as acylating agents and Zn(OAc)2 as a catalyst, 1,2-diols, 1,3-diols, and catechol were selectively monoacylated. Furthermore, the highly enantioselective desymmetrization of meso-tartrates was achieved for the first time, utilizing 2-pyridyl esters and NiBr2/AgOPiv/Ph-BOX in CH3CN or CuCl2/AgOPiv/Ph-BOX in EtOAc catalyst systems (up to 96% ee). The latter catalyst system was also effective for the kinetic resolution of dibenzyl dl-tartrate.
Synthesis and chiroptical properties of a new type of chiral depsipeptide dendrons
Buschhaus, Boris,Bauer, Walter,Hirsch, Andreas
, p. 3899 - 3915 (2007/10/03)
A new type of chiral depsipeptide dendrons based on tartaric acid as branching juncture and ω-aminocapronic acid as spacer has been prepared. Natural and unnatural tartaric acid building blocks have been incorporated, providing access to combinatorial libraries. All compounds have been completely characterized by FAB-MS, EA analysis, 1H/13C NMR- and UV/Vis-spectroscopy. 1H NMR relaxation measurements have been used to examine the conformational flexibility of these dendrons in CH3CN and CH3OH and indicate a less flexible structure in CH3CN. Pulse gradient spin echo (PGSE) NMR measurements correlate these findings to molecular dimensions. A reduced size for the dendrons in CH3CN compared to CH3OH leads to the assumption of a more compact structure in this solvent. Additional polarimetric data reveal, that observed changes in optical activity with increasing generation can in CH3OH be explained by constitutional effects of the dendron structure but not in CH3CN. CD measurements are in agreement with these findings and show a linear increase of the Cotton effects with increasing generation for CH3OH but not for CH3CN. It can be concluded that the conformation within the dendrons is very sensitive to environmental conditions and that a chiral secondary structure might be stabilized in CH3CN. Initial studies revealed that chirality transfer to the focal functionality occurs.
Reductive Cross Coupling Reaction of a Glyoxylate with Carbonyl Compounds. A Facile Synthesis of α,β-Dihydroxycarboxylate Based on a Low Valent Titanium Compound
Mukaiyama, Teruaki,Sugimura, Hideo,Ohno, Takashi,Kobayashi, Shu
, p. 1401 - 1404 (2007/10/02)
On treatment with a low valent titanium compound, a glyoxylate is reductively converted to the titanium enediolate, which reacts with carbonyl compounds to give the corresponding adducts, α,β-dihydroxycarboxylates, in good yields.
