ChemInform Abstract: SYNTHESIS OF (4H)‐1,3‐BENZODIOXIN‐2‐CARBOXYLIC ACIDS AND ESTERS AND STUDY OF THEIR HYPOLIPEMIC ACTIVITY

Abstract

Insgesamt 28 Diole des Typs (II) und 61 Benzodioxincarbonsäuren(‐säureester) des Typs (IV) wurden auf verschiedenen Wegen dargestellt, darunter RU 24728 (IVa) (trans bezüglich der Gruppen ‐Ph und ‐COOH), RU 25247 (IVb) (trans) und 25961 (IVd) (trans), und auf ihre hypolipämische Aktivität untersucht.

Apolar versus Polar Solvents: A Comparison of the Strength of Some Organic Acids against Different Bases in Toluene and in Water

“…The above-reported 2,2-dichloroalkanoic acids (and their derivatives) are valuable and versatile substrates in organic chemistry. This is due to their bifunctional structure, R−CCl 2 −COY, which provides these molecules with a number of interesting features, such as, the easy nucleophilic acyl substitution at the carboxylic CO, the smooth generation of radicals , or of α-halo enolates, the dehydrohalogenation to α-chloroacrylic monomer, and the possibility of nucleophilic transformations of the Cl,Cl−acetal group. , …”

Origin of Enantiomeric Selectivity in the Aryloxyphenoxypropionic Acid Class of Herbicidal Acetyl Coenzyme A Carboxylase (ACCase) Inhibitors

“…Two general precedented approaches to the targeted molecules were revealed through retrosynthetic analyses ( Figure ). The materials that contain two oxygen atoms attached directly to the α-carbon of the acetate moiety ( 7 , 8 ) should be available through condensation of the appropriate diol with a dihaloacetic acid ( , ). The remaining two materials, 6 and 9 , could conceptually be prepared through intramolecular nucleophilic ring opening of an epoxide by a phenolic hydroxyl followed by adjustment of the oxidation state of the resulting alcohol ( − ).…”

“…benzodioxin-2-yl]methanol(26). A mixture of 7.67 g (19 mmol) of acetate 25, 8.40 g (21 mmol) of 10% aqueous NaOH, and 25 mL of THF was stirred under N2 at ambient temperature for 2 days.…”

“…Regioselective alkylation of one of the two hydroxyls of catechol 12 was required in order to make effective use of the epoxide ring opening strategy for preparation of the remaining targeted acids, dihydrobenzo-1,4-dioxins 9 and 21. In practice, this was achieved through utilization of acetophenone 22 as a masked form of 1,2,4-trihydroxybenzene (Scheme 4) (26). The acetophenone was first condensed with pyridine 10 to provide phenol 23 as the sole isolable product.…”

“…The requisite "regioselective" alkylation was then achieved by reaction of this phenol with epichlorohydrin to give disubstituted acetophenone 24. The new phenol was finally revealed, as its acetate, by Baeyer-Villiger oxidation of 24; base-catalyzed hydrolysis of the resulting epoxy acetate (25) resulted in simultaneous deesterification and cyclization to form the dioxin ring (26). Attempted oxidation of the primary alcohol of 26 under a variety of standard conditions (Jones reagent, PCC, Swern) failed to provide the desired acid product, 9, or the corresponding aldehyde.…”