The hydrolysis of α,α'‐dimethoxydihydrofurans

Abstract

A series of α,α ‐dimethoxydihydrofurans have been prepared and subjected to various acidic and neutral hydrolysis conditions in attempts to prepare conjugated enediones in a stereospecific manner. Isomerization of the 3‐hexene‐2,5‐diones and rearrangements of other enediones to β,γ‐unsaturated‐γ‐lactones have been uncovered. Methods of assignment of stereochemical configuration to the enediones are evaluated; reaction with hydrazine hydrate in the absence of acid is proposed as a useful criterion.

Reactive intermediates in the oxidation of menthofuran by cytochromes P-450

“…Of the remaining molecules, most incorporated 1 atom of oxygen from molecular oxygen and 1 atom was retained from the substrate, menthofuran. Two chemical reactions that apparently proceed through the 7-ketoenal (31,32) yielded mintlactone that mostly 6 Values represent the relative composition (%) of mintlactone formed by the incorporation of 0, 1, or 2 atoms of oxygen from water in the incubation medium; means ± SD. contained 2 atoms of oxygen derived from water.…”

Synthesis of 2,5-dihydroxy-2,5-dihydrofurans by anodic oxidation of furans

“…Only the N-alkylation product 4 was isolated. Hydrogenation of this product furnished 2,2-dimethyl-l,2,3,4-tetrahydroisoquinoline iodide (5), the same as the material obtained by methylating 2methyl-l,2,3,4-tetrahydroisoquinoline (3).11 Our results with the simplest alkyl group and the parent dihydroisoquinoline, therefore, agree with the tendency noted before for eneamine alkylation with alkyl halides to favor nitrogen rather than carbon.12•13 Experimental Section 2-Methyl-l,2-dihydroisoquinoline (2). 2-Methylisoquinolinium iodide (8.1 g; 0.030 mol) was added in one portion to a stirred suspension of lithium aluminum hydride (1.2 g; 0.030 mol) in 150 ml of ether protected with a blanket of nitrogen.…”

Six‐Membered Heterocycles: 1,2‐, 1,3‐, and 1,4‐Diazines and Related Systems

“…Release of the adducts from the resin occurs by spontaneous elimination driven by ring aromatization. Unsaturated 1,4-dicarbonyls likewise undergo cyclization with hydrazine to afford directly the pyridazine product 42 (Scheme 19.11) [33]. While (Z)-alkenyl diketones react readily with ethanolic hydrazine hydrate at room temperature, cyclization of the corresponding (E)-isomer also occurs but requires higher reaction temperatures [34].…”