A Mild Stereo‐ and Enantiospecific Conversion of 2,3‐Diaryl‐Substituted Oxiranes into 2,2‐Dimethyl‐1,3‐Dioxolanes by an Acetone/Amberlyst 15 System

Abstract

Amberlyst 15 is an efficient catalyst for the reaction of aryl‐substituted oxiranes with acetone to prepare 2,2‐dimethyl‐1,3‐dioxolanes in high yields. trans‐2,3‐Diaryloxiranes afford trans‐acetonides enantiospecifically at room temperature, and the use of enantiopure 2,3‐diaryloxiranes results in no loss of stereochemical integrity in the resulting trans‐acetonides. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Controlling Selectivity in Alkene Oxidation: Anion Driven Epoxidation or Dihydroxylation Catalysed by [Iron(III)(Pyridine‐Containing Ligand)] Complexes

“…[25] Among the catalysts used, both Fe(OTf) 3 [26] and anhydrous FeCl 3 [27] salts were reported to promote this reaction with good yields. Epoxides can be readily converted into acetonides in the presence of catalytic amounts of Lewis acids in acetone as solvent.…”

“…Epoxides can be readily converted into acetonides in the presence of catalytic amounts of Lewis acids in acetone as solvent. [25] Among the catalysts used, both Fe(OTf) 3 [26] and anhydrous FeCl 3 [27] salts were reported to promote this reaction with good yields. On the other hand, it is well known that strong acids can readily open epoxides.…”

A Novel Approach to Combretastatins: From trans‐Epoxide to CA‐4 and Its Dioxolane Derivative

“…In order to test the synthetic scope of such an intermediate we submitted epoxide 4 to our recently developed regio-and stereoselective ring-opening reactions, which were efficient on various trans 2,3-diarylepoxides. [13] In particular, the LiBr/Am-berlyst 15 system [13b,14] afforded ketone 8 through acid-promoted rearrangement of the epoxide. In contrast, the direct conversion into trans-dioxolane 9 by the acetone/Amberlyst 15 system…”

“…Chromatographic purification of the crude on silica gel (petroleum ether/diethyl ether, 6:4) gave 110 mg (57 % yield) of pure 10 as an oil.144 H) ppm. 13 5-(3-tert-Butyldimethylsilyloxy-4-methoxystyryl)-1,2,3-trimethoxybenzene (11): A solution of trans-stilbene 10 (50 mg; 0.1 mmol) in acetone (20 mL) was irradiated at λ = 254 nm at room temperature. After 44 h, the irradiation was stopped and the solvent was evaporated.…”

Oxone–acetone mediated syn-dioxygenation of benzo-fused olefins

“…Similarly, cis-stilbene gave the corresponding cis-acetonide and cis-epoxide. 16 This observed stereospecific 1,3-dioxlane formation further suggests that the epoxide may not be involved as an intermediate in this process.…”