Synthesis of Verrucarin A and 3α‐Hydroxyverrucarin A from Verrucarol and Diacetoxyscripenol (Anguidine). 39th Communication on Verrucarins and Roridins

Abstract

The title compounds have been synthesized starting from verrucarol and diacetoxyscripenol (anguidine), (E, Z)‐muconic half ester and a derivative of verrucarinic acid. The latter has been prepared in optically active form from dimethyl 3‐methylglutarate.

Synthesis of New unnatural Macrocyclic Trichothecenes: 4‐epiverrucarin A. 47th Communication on verrucarins and roridins

“…Having obtained 4-epiverrucaro1(20), we decided to synthesize 4-epiverrucarin A (24) by the same route as that used in the synthesis of verrucarin A [13]. We planned to begin with the selective esterification of the 15-OH group with the verrucarinic-acid derivative 25 and accordingly to attach the muconic halfester 26 to the remaining 4-OH group.…”

“…The muconates 30 and 31 were obtained with a yield of 61 and 29%, respectively, without isomerization of the (Z)-double bond (cf. [13]). However, the condensation of the primary OH group in 30 with the acid 25 turned out to be more difficult: 2.5 equiv.…”

Ionization Shifts in 1H‐NMR Spectra of α,β‐Unsaturated Carboxylic Acids

“…Nevertheless, using appropriate model compounds, the ionization shifts can be used for immediate identification of 'H resonances in olefinic acids. For the purpose of the present work, the reference data reported in Tables I and 2 provide sufficient basis to prove unambiguously the structures of monoesters of (2E,42)-2,4-hexadienedioic acid, such as 12 and 13, of interest in connection with synthetic studies on verrucarins [7].…”

“…Limited information about such ioni- zation shifts is available [4] [ 5], in spite of their potential utility as an aid to structure determination by 'H-NMR spectroscopy [6]. Here, we report on the ionization shifts of olefinic H-atoms in a number of a$-and a,P,y,b-unsaturated carboxylic acids, and demonstrate their practical usefulness in determination of structures of monoesters of (2E,4Z)-2,4-hexadienedioic acid, which are of interest as building blocks in syntheses of verrucarins [7].…”

Methanophenazin: Strukturaufklärung und Totalsynthese eines neuartigen Cofaktors aus methanogenen Archaea

“…Damit sind chirale Substanzen wie (R)-11 begehrte Bausteine für die Synthese von Verbindungen wie α-Tocopherol [78] oder Verrucarinsäure. [79] Die Gewinnung des mittlerweile im Handel erhältlichen (R)- Ein eleganter Ansatz zur Gewinnung chiraler Verbindungen aus prochiralen Vorläufern nutzt die Fähigkeit von Enzymen wie α-Chymotrypsin, [81] Schweineleber-Esterase [82] und Pferdeleber-Alkoholdehydrogenase, [83] enantiotopdifferenzierende Reaktionen zu silylieren. [84] Bei dem Versuch diese Transformationen durchzuführen, stellten sich gleich zu Beginn Schwierigkeiten ein.…”