Synthese von vier chiralen, elektrophilen C₃‐ und C₄‐Synthesebausteinen aus Hydroxycarbonsäuren

Abstract

Synthesis of four chiral electrophilic C3-and C4-synthons from hydroxycarboxylic acids SummaryThe chiral alkylating reagents 4, 642, and 10a/b are prepared from lactic, /3-hydroxy butyric, and malic acid, respectively. Their use in natural product synthesis is referred too.Die Natur stellt uns eine Vielzahl von einfachen, optisch reinen Verbindungen wie Milchsaure, Apfelsaure, Weinsaure, Aminosauren und Zucker zur Verfugung, aus denen wir wie aus einer schier unerschopfllichen Quelle (chiral ~001)s) chirale Bausteine zur Synthese von komplizierteren Natur-und Wirkstoffen schopfen konnen. Dieses Vorgehen bei der Synthese enantiomerenreiner Zielmolekeln umgeht sowohl die Enantiomerentrennung, als auch die Suche nach wirksamen enantioselektiven Umsetzungen [3]. Nachdem wir in fruheren Arbeiten uber Bausteine aus der -wegen der leichten Zuganglichkeit beitler Antipoden -besonders (

The World of β‐ and γ‐Peptides Comprised of Homologated Proteinogenic Amino Acids and Other Components

“…There was no time for synthetic elegance or method development 44 ). With the existing methods, it was necessary to use up to a dozen reaction steps, in order to prepare the −simple×, enantiomerically pure b-amino acids functionalized in their side chains with suitable protection!…”

“…43 ) See [273] [274] and the earlier publications by van Gunsteren×s group cited therein. 44 ) The strict standards defined by P. Fuchs for synthetic efficiency (IQ and EQ coefficients) could also not be claimed [275]. Chiral dihydropyrimidinone, Heck reaction, and hydrogenation [334] review with key literature citations is given in Fig.…”

Enantiospecific synthesis of optically pure (S)-(+)-3-hydroxy-1-phenyl-1-butanone by bakers' yeast reduction

“…We also prepared this racemate by double reduction of 1-phenyl-1,3-butanedione with sodium borohydride followed by selective oxidation of the benzylic alcohol with pyridinium dichromate (eq. [2]). (Fig.…”

(R)-(+)-2-Phenylpropyl p-toluenesulfonate, C16H18O3S

“…(S)-(-)-Ethyl lactate is particularly attractive as a chiral synthon as it is readily available in both enantiomeric forms with very high optical purity and, therefore, has been used in numerous applications (Seuring & Seebach, 1977). Recently, we described an efficient method for the preparation of (R)-(-)-p-(2-methylhexyl)aniline, (1), from (S)-(-)-ethyl lactate (Medo & Gallardo, 1993), which is of considerable interest as a building block for liquid-crystalline materials having ferroelectric properties.…”