A regio- and stereo-selective reduction of diketo-n-butylphosphonates by baker's yeast was reported. The chemical yield and ee value of these reactions are highly dependent on the structure of substrates. The re...A regio- and stereo-selective reduction of diketo-n-butylphosphonates by baker's yeast was reported. The chemical yield and ee value of these reactions are highly dependent on the structure of substrates. The resulting optical active hydroxy^alkanephosphonates can be used as chirons for the synthesis of polyfunctional organophosphorus compounds. As useful building block, a series of α,β-unsaturated ketones bearing chiral hydroxy group in addition to trifluoromethyl moiety was prepared via the Horner-Wadsworth-Emmons (HWE) reaction of the biotransformation products.展开更多
Coupling of acetylated α-(1→3)-linked glucobiosyl trichloro-acetimidate with acetylated α-(1→3)-linked glucobioside acceptor gave a β-linked tetrasaccharide, while coupling of acetylated β-(1→3)-linked glucobio...Coupling of acetylated α-(1→3)-linked glucobiosyl trichloro-acetimidate with acetylated α-(1→3)-linked glucobioside acceptor gave a β-linked tetrasaccharide, while coupling of acetylated β-(1→3)-linked glucobiosyl trichloroacetimidate with acetylated β-(1→3)-linked glucobioside acceptor gave an α-linked tetrasaccharide in spite of the C-2 neighboring group participation. Two hexasaccharides with alternative (1→3)-α- and -β-linkges were synthesized by these reactions via remote control exerted by the glycosylation bond in either donor or acceptor.展开更多
文摘A regio- and stereo-selective reduction of diketo-n-butylphosphonates by baker's yeast was reported. The chemical yield and ee value of these reactions are highly dependent on the structure of substrates. The resulting optical active hydroxy^alkanephosphonates can be used as chirons for the synthesis of polyfunctional organophosphorus compounds. As useful building block, a series of α,β-unsaturated ketones bearing chiral hydroxy group in addition to trifluoromethyl moiety was prepared via the Horner-Wadsworth-Emmons (HWE) reaction of the biotransformation products.
文摘Coupling of acetylated α-(1→3)-linked glucobiosyl trichloro-acetimidate with acetylated α-(1→3)-linked glucobioside acceptor gave a β-linked tetrasaccharide, while coupling of acetylated β-(1→3)-linked glucobiosyl trichloroacetimidate with acetylated β-(1→3)-linked glucobioside acceptor gave an α-linked tetrasaccharide in spite of the C-2 neighboring group participation. Two hexasaccharides with alternative (1→3)-α- and -β-linkges were synthesized by these reactions via remote control exerted by the glycosylation bond in either donor or acceptor.
