Chirale elektrophile Synthesebausteine mit vier verschiedenen funktionellen Gruppen aus Weinsäure, 2, 3‐ und 3, 4‐Epoxy‐butandiolderivate in allen vier stereoisomeren Formen

Abstract

Efficient and simple procedures have been developed for the preparation of the threo-and erythro-3,4-epoxy-1,2-butanediol derivatives 3 and 8 and of the cis-and trans-2,3-epoxy-1,4-butanediol derivatives 7 and 9 in both enantiomeric forms from tartaric acid (see Scheme 2 ) . These epoxides should prove versatile as alkylating reagents in syntheses of enantiomerically pure natural products and of physiologically active compounds.

Intramolecular Diels−Alder/Tsuji Allylation Assembly of the Functionalized trans-Decalin of Salvinorin A

“…The trans -decalin 3 , bearing a quarternary center stereocenter at the C5 ring fusion could be obtained via a diastereoselective intramolecular Diels−Alder (IMDA) reaction from the enone 4 . The tartaric acid derivative 5 was identified as a useful precursor to 4 . This would involve carbon−carbon bond formation by a regioselective allylic dithiane anion alkylation, Horner−Wadsworth−Emmons (HWE) olefination, and O-acylation of the resultant ketone enolate.…”

“…The synthesis of the IMDA substrate enol carbonate 4 shown in Scheme started with 2-(propan-2-ylidene)-1,3-dithiane 6 (synthesized in two steps from 1,3-dithiane) and the known iodide 5 , which was prepared in four steps from l -(+)-tartaric acid. Dithiane 6 was α-alkylated via its lithium anion with iodide 5 , and subsequent silyl ether cleavage with TBAF gave compound 7 with no evidence of δ-alkylation.…”

Modification of the membrane‐bound glucose oxidation system in Gluconobacter oxydans significantly increases gluconate and 5‐keto‐D‐gluconic acid accumulation

“…5-KGA can be efficiently converted into L-(+)-tartaric acid by a noble metal catalyst [8,9]. L-(+)-Tartaric acid is important for the chemical, food and textile industry, where it has many applications, e.g., as an antioxidant and acidulant in food, a chiral precursor in stereoselective organic synthesis, and an acidic reducing agent in textile dyeing [10][11][12]. According to Matsushita et al [5], G. oxydans contains two different enzyme systems for oxidizing glucose: one glucose oxidation system is located in the cytosol and consists of the soluble NADP + -dependent enzymes glucose-dehydrogenase (GDH), and gluconate:NADP 5-oxidoreductase ( Fig.…”

Synthesis and late stage modifications of Cyl derivatives

“…Chiral allylic alcohols are easily accessible, either via kinetic resolution of racemic alcohols [46,47], asymmetric catalysis [48], or from chiral pool materials, such as threitol 1 [49]. Using the last approach, 1 was mono-O-allylated to 2 under similar conditions reported previously for monobenzylation (Scheme 3) [50]. Iodination (3) and subsequent elimination of the iodide with zinc dust gave allylic alcohol 4 as a single enantiomer, which was esterified with Boc-protected glycine to allyl ester 5.…”