“Instant Methylide” Modification of the Corey–Chaykovsky Epoxide Synthesis

Direct Asymmetric α‐Sulfamidation of α‐Branched Aldehydes: A Novel Approach to Enamine Catalysis

“…[73] In the case of the electron-rich aldehyde 26, in which acidic cleavage did not provide the desired product, the corresponding alcohol was prepared by hydroboration either of the enol ether or of the analogous styrene, [74] obtained in a Wittig reaction with methyltriphenylphosphonium bromide, followed by Dess-Martin oxidation to give the desired aldehyde. [75] Alternatively, the corresponding acetophenone can be converted into an epoxide in a Corey-Chaikovsky procedure, [76] and this then can be opened by an indium(III)-catalysed rearrangement to afford the desired starting material. [77] In the case of the achiral aldehydes 14-17, yields between 36 % and 52 % were obtained (Table 6, Entries 1-4).…”

Three‐Membered Heterocycles. Structure and Reactivity

“…Thus, combination of 4-methylacetophenone (470, Scheme 2.72) with the instant methylide reagent in dimethyl sulfoxide (DMSO) resulted in the high-yielding formation of the corresponding epoxide 471 [513]. The Corey-Chaykovsky epoxidation has also been adapted for use in an ionic liquid medium, such as (bmim)PF 6 [514].…”

Synthesis of Hexahydrocyclopenta[c]furans by an Intramolecular Iron‐Catalyzed Ring Expansion Reaction

“…Therefore, very little attention was applied to control the stereochemistry in the olefination reaction. The formation of the epoxide subunit could then be realized by the addition of a simple sulfur ylide [8] affording the desired epoxyalkene 1 in a relatively short reaction sequence and leaving considerable flexibility for the access of differently substituted starting materials. With the terminal alkene functionality (R = H, 1g) a ruthenium-catalyzed cross-metathesis reaction led to products (1k, 1l) not chemoselectively accessible by the regular Wittig olefination route.…”