Versuche zur Synthese isomerer Methyltocole

Abstract

Bisher ist ein einziges Monomethyl-tocol bekannt l ) , das die Methylgruppe in Stellung 8 enthiilt. Die Schwierigkeit der Darstellung der beiden anderen Isomeren (5-sowie 7-Monomethyl-tocol) liegt darin, dass zur Zeit keine Methode existiert, zwei Stellungen im Toluhydrochinon vorubergehend so zu blockieren, dass die dritte Stelle bei der Tocolsynthese in Reaktion treten muss, und nachher die vorubergehend eingefuhrten Substituenten wieder zu entfernen. Dieses Problem bildete den Ausgangspunkt fur die folgenden Versuche.In der Einwirkung von Ramy-Nickel besitzt man heute ein einfaches Verfahren, um aus organischen Schwefelverbindungen die schwefelhaltige Gruppe reduktiv zu eliminieren. Wir versuchten daher, Methylmercaptoderivate des Toluhydrochinons herzustellen, diese mit Phytol zu den entsprechenden Methyl-methylmercaptotocolen zu kondensieren und aus letzteren nachtriiglich die Methylmercaptogruppe mittels Raney-Nickel zu entfernen, z. B.

A year away to 100th year of vitamin E synthesis

“…They started with toluhydroquinone 31 and further 2‐mercapto‐5‐methylbenzene‐1,4‐diol 34 was obtained in two steps. Condensation reaction was undertaken thereafter with phytol 4 followed by desulfurization reaction on 35 with Raney Ni to afford δ‐tocopherol as product (Scheme 10) [63].…”

The biological activities of ε- and ζ-tocopherols

“…In order to estimate the vitamin E activity of any food, it is necessary to have a knowledge of both the relative biological activities and the individual amounts of the various forms of tocopherol present. Although e-tocopherol has been synthesized (Karrer & Dutta, 1948), there is no published information about its biological activity. It has been suggested by Eggitt & Norris (1956), however, that from its chemical constitution it should have the activity of P-tocopherol or about 30% of that of a-tocopherol.…”

Estudos de diastereosseletividade facial em reações de Diels-Alder de sulfinil benzoquinonas e em adições nucleofílicas a sulfinil cicloexanonas sulfaniladas

“…A primeira alquilação estereosseletiva, bem sucedida, de um α-sulfinil carbânion foi realizada por Marquet e col., 21 Em vista do resultado apresentado acima, pensamos em preparar a (±)-2,6-dimetil-3-p-tolilsulfinil-1,4-benzoquinona (75) e estudar a sua Diels-Alder com o 1-vinil- 44 Dickinson Ao produto minoritário, Karrer e Dutta, 56 inequivocamente, atribuíram a estrutura 86 pela comparação de suas características físicas com aquelas do produto obtido por uma via independente, a partir da 5-metil-2-(metiltio)anilina.…”