- Selective Monoacylation of Diols and Asymmetric Desymmetrization of Dialkyl meso-Tartrates Using 2-Pyridyl Esters as Acylating Agents and Metal Carboxylates as Catalysts
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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.
- Hashimoto, Yuki,Michimuko, Chiaki,Yamaguchi, Koki,Nakajima, Makoto,Sugiura, Masaharu
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p. 9313 - 9321
(2019/08/12)
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- Aldol reactions of ketal-protected tartrate ester enolates. Asymmetric syntheses and absolute stereochemical assignments of phospholipase A2 inhibitors cinatrin C1 and C3
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An efficient approach to the syntheses of cinatrins C1 and C3 has been developed and used to establish the absolute configurations of these natural products. The construction of each molecule has been achieved in a five-step reaction sequence (overall yield 43% for cinatrin C1, 33% for cinatrin C3) from the di-tert-butyl ester of (R,R)-tartaric acid. The two contiguous, quaternary chiral centers in the cinatrin skeleton are constructed via a diastereoselective, titanium-mediated aldol coupling of a tartrate-derived silylketene acetal and an achiral α-ketoester. This bond construction proceeds with excellent diastereoselectivity for a variety of aldehyde and α-ketoester substrates.
- Evans, David A.,Trotter, B. Wesley,Barrow, James C.
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p. 8779 - 8794
(2007/10/03)
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