Furyl(aryl)alkanes and Their Derivatives. 19. Synthesis of Benzofuran Derivatives via 2-Hydroxyaryl-R-(5-methylfur-2-yl)methanes. Reaction of Furan Ring Opening - Benzofuran Ring Closure Type

Abstract

2-Hydroxyaryl(5-methylfur-2-yl)alkanes synthesized by alkylation of 2-methylfuran with various 2-hydroxybenzylic alcohols, were rearranged into corresponding 3-R-benzo [b]furan derivatives by treatment with ethanolic HCl solution. These compounds can not be transformed into dibenzoxazulenium salts.

Reaction Products of γ-Tocopherol with (E)-4-Oxo-2-nonenal in Acidic Acetonitrile

“…23) Intramolecular nucleophilic addition between the 4-hydroxyl and 1-carbonyl groups of the enol molecule would then give a cyclic hemiacetal intermediate. If -tocopherol is present in the reaction mixture, the C-5 position of -tocopherol could attack the double bond at the C-5 A reaction mixture of -tocopherol (10 mM) and 2-(1-hydroxypentyl)furan (20 mM) in acetonitrile was incubated at 37 C for 3 h in the absence (A) or presence (B) of 50 mM HCl. The reaction mixture was extracted with hexane and analyzed by reversed-phase HPLC as described in Fig.…”

“…-Tocopherol was reacted with (E)-4-oxo-2-nonenal (ONE) at 37 C in an acidic acetonitrile solution. The reaction products were isolated by reversed-phase high-performance liquid chromatography and their structures were characterized to be 5-substitutedtocopherols: 5-(1-(furan-2-yl)pentyl)--tocopherol (1), 3-(1-butyl-4,5,7-trimethyl-7-(4,8,12-trimethyltridecyl)-8,9-dihydro-7H-furo[3,2-f]chromen-2yl)propanal (2), and 1-(1-butyl-4,5,7-trimethyl-7-(4,8,12-trimethyltridecyl)-8,9-dihydro-7H-furo[3,2-f]chromen-2-yl)-4-(furan-2-yl)octan-3-one (3).…”

4,5-Dimethoxy-2-nitroacetophenone

“…The general part of the experimental section [1] has been presented elsewhere. To solution of 4,5-dimethoxyacetophenone (20.0 g, 110 mmol) in 45 ml of glacial acetic acid, red fuming nitric acid (22.0 ml) was added dropwise with cooling in an ice-water bath.…”

4,5-Dimethoxy-2-nitrobenzophenone

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The general part of the experimental section [1] has been presented elsewhere. To a solution of 4,5-dimethoxybenzophenone (3.0 g, 12.4 mmol) in 7 ml of glacial acetic acid, red fuming nitric acid (3.4 ml) was added.

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