The Synthesis of Chiral α-Aryl α-Hydroxy Carboxylic Acids via RuPHOX-Ru Catalyzed Asymmetric Hydrogenation
A ruthenocenyl phosphino-oxazoline-ruthenium complex (RuPHOX?Ru) catalyzed asymmetric hydrogenation of α-aryl keto acids has been successfully developed, affording the corresponding chiral α-aryl α-hydroxy carboxylic acids in high yields and with up to 97% ee. The reaction could be performed on a gram scale with a relatively low catalyst loading (up to 5000 S/C) and the resulting products can be transformed to several chiral building blocks, biologically active compounds and chiral drugs. (Figure presented.).
AUXILIARY SRTUCTURE AND ASYMMETRIC INDUCTION IN THE "MUKAIYAMA-ALDOL" REACTIONS OF CHIRAL SILYL KETENE ACETALS
A variety of chiral auxiliaries R*OH were prepared and tested for levels of asymmetric induction control in the "Mukaiyama-aldol" reaction of chiral silyl ketene acetals.Structural features required for high levels of control are discussed.
ON CARBONYL PARTICIPATION IN THE SOLVOLYSES OF α-KETO MESYLATES
α-amido mesylates generally solvolyze giving α-keto cations, bypassing cyclic ions derived from carbonyl (kΔ) participation.A possible exception is the N,N-dimethylamido mesylate derived from (S)-mandelic acid in trifluoroacetic acid which gives a small amount (9percent) of retained product.
Creary, Xavier,McDonald, Steven R.,Eggers, Mark D.
p. 811 - 814
(2007/10/02)
Preparation and activity of -substituted acetylcholine iodides.
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Cocolas,Robinson,Dewey,Spaulding
p. 1749 - 1752
(2007/10/06)
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