Über 1.3‐Dioxolane, I. Darstellung von 2‐Alkoxy‐1.3‐dioxolanen

Abstract

Durch Umsetzung von 1.2‐Glykolen mit Orthoameisensäure‐trialkylestern in Gegenwart katalytischer Mengen konz. Schwefelsäure wurde eine Reihe von 2‐Alkoxy‐1.3‐dioxolanen dargestellt, in denen weiterhin durch Umsetzung mit prim. Alkoholen unter denselben Versuchsbedingungen die 2‐Alkoxygruppe ausgetauscht werden konnte. 1.3‐Glykole führten zur Bildung von 2‐Alkoxy‐1.3‐dioxanen, Brenzcatechin zu 2‐Alkoxy‐4.5‐benzo‐1.3‐dioxolan.

Tetracyclines. 10. Chemical-structural properties of tetracycline derivatives. 5. A total synthesis and structural aspects of racemic 8-oxygenated tetracyclines

“…Reduction with hydridodiisobutylaluminum, highly successful in an analogous step of our aureomycin synthesis16 and upon application to ethanediyl 5,5-acetal 29 (see below), led exclusively to eliminative cleavage of the acetal function. Finally, reduction of nitrile 22 with Raney nickel in a slightly acidic aqueous buffer system afforded the aldehyde 24 in 74% yield. The literature contains several examples of nitriles being reduced to aldehydes by Raney nickel in the presence of another reducing agent,25 such as sodium hypophosphite, formic acid, or elemental hydrogen.…”

Ortho Esters

“…The use of 1,2-and 1,3-diols in the transesterification reaction provides a means of providing monocyclic ortho esters [49][50][51][52][53][54]. Cycloalkanediols, cate chol [54c], or acyclic triols result in bicyclic [55] and polycyclic ortho esters [56,57] …”

“…(50) Preparation of ortho esters by the electrochemical methoxylation of acetals [217]. (51) Reaction of methyl perfluoroacetate with sodium methylate followed by reaction with methyl sulfate to give CF 3 C(OCH 3 ) 3 [218]. (52) Preparation of m-iodoorthothiobenzoate by the reaction of m-iodobenzoyl chloride with ethanethio and A1C1 3 .…”

Reactions of Ortho Esters Which Result in Carbon-Oxygen and Carbon-Halogen Bond Formation

“…2-Alkoxy-1,3-dioxolanes hydrolyze rapidly in the presence of aqueous mineral acids (19,74,299). Various bicyclic and polycyclic dioxolanes also undergo facile acid hydrolysis.…”