Formation stéréocontroˆlée de deux centres chiraux contigus par thio-rearrangement de claisen d'α-hydroxydithioacétals de cétène s-allylés.
作者:Pieire Beslin、Stéphane Perrio
DOI:10.1016/s0040-4020(01)86559-5
日期:1991.8
assignments were confirmed by a syn selective aldol reaction of 4-pentenedithioates with the appropriate aldehydes. A few 13C NMR generalization rules allowing syn and anti configuration determination were also put forth. A transition state model is proposed to explain the observed asymmetricinduction by the external hydroxy group as a result of both steric and stereoelectronic control.
Über die Stereospezifität der α-Alkylierung von β-Hydroxycarbonsäureestern. Vorläufige Mitteilung
作者:György Fráter
DOI:10.1002/hlca.19790620832
日期:1979.12.12
About the Stereospecific α-Alkylation of β-Hydroxyesters
关于β-羟基酯的立体特异性α-烷基化
Systematic Investigation of <i>Saccharomyces </i><i>c</i><i>erevisiae</i> Enzymes Catalyzing Carbonyl Reductions
作者:Iwona A. Kaluzna、Tomoko Matsuda、Aileen K. Sewell、Jon D. Stewart
DOI:10.1021/ja0469479
日期:2004.10.1
each purified fusion protein. The stereoselectivities of beta-keto ester reductions depended both on the identity of the enzyme and the substrate structure, and some reductases yielded both L- and D-alcohols with high stereoselectivities. While alpha-keto esters were generally reduced with lower enantioselectivities, it was possible in all but one case to identify pairs of yeast reductases that delivered
The product of Baker's yeast reduction of ethyl 2-chloro-3-oxobutanoate as a precursor of the 1-ethoxycarbonyl 2(S)-hydroxypropyl radical
作者:Mourad Hamdani、Bernard De Jeso、Hervé Deleuze、Annie Saux、Bernard Maillard
DOI:10.1016/s0957-4166(00)80233-5
日期:1993.6
Baker's yeast treatment of ethyl 2-chloro-3-oxobutanoate 1, diethyl 2-acetylmalonate 2 and ethyl 2-cyano-3-oxobutanoate 3 was effected in order to obtain enantiomerically enriched compounds. In contrast to the reaction of 2 and 3, efficient diastereo- and enantioselective reduction of 1 provided ethyl 2(R)-chloro-3(S)-hydroxybutanoate. This product was used as precursor of the 1-ethoxycarbonyl-2(S)-hydroxypropyl
Application of stereocontrolled aldol coupling to synthesis of segments of immunosuppressants FK-506 and rapamycin
作者:James D. White、Jörg Deerberg、Steven G. Toske、Takayuki Yakura
DOI:10.1016/j.tet.2009.06.030
日期:2009.8
The sector comprising C24–C34 of FK-506 containing five of the stereogenic centers in this macrolide was synthesized from (−)-quinic acid. Aldol coupling of the C24–C34 unit with a methyl ketone representing C20–C23 of FK-506 proceeded with complete Felkin stereoselectivity to afford the C20–C34 portion of the immunosuppressant. A chelate transition state invoking coordination of a lithium enolate