Stereoselective Synthesis of Cyclic Ethers by Intramolecular Trapping of Dicobalt Hexacarbonyl-Stabilized Propargylic Cations

Abstract

The intramolecular attack of a hydroxy group on an exo-biscobalthexacarbonyl propargylic cation provides cyclic ethers with six- to nine-membered rings. The scope and limitations of the methodology are described. The reaction is stereoselective when additional stereocenters are present, providing iterative methodology to access ladder-like cyclic ethers.

Epoxide‐Opening Cascades Triggered by a Nicholas Reaction: Total Synthesis of Teurilene

“…To address this problem, Jamison et al used a bromonium-initiated epoxide-opening cascade in the synthesis of ent-dioxepandehydrothyrsiferol. [11] Within our program directed to the synthesis of biologically active molecules and the development of new synthetic methodologies, [12] we became interested in the synthesis of teurilene (1), thyrsiferol (2), and their congeners. Teurilene (1) is a squalene-derived triterpene polyether isolated by Kurosawa et al from the red algae Laurencia obtusa along with thyrsiferol (2) and its acetyl derivative thyrsiferyl 23acetate (3; Figure 1).…”

The tert-butyl dimethyl silyl group as an enhancer of drug cytotoxicity against human tumor cells

“…These heterocycles are common intermediates in our stereoselective synthesis of cyclic ethers and were selected as model for our study. 8 The rationale behind our strategy is to introduce lipophilicity by the addition of another moiety, the tert-butyl dimethyl silyl (TBS) group. This silicon scaffold was selected because it is widely used in synthetic organic chemistry as a protecting group of hydroxyl groups.…”

Strategies for the Synthesis of Cyclic Ethers of Marine Natural Products

“…67 Also, by using this methodology, we were able to obtain an oxaneoxepane system (Scheme OBn; n = 3), we needed at least two geometric control elements: a ring and a Z-double bond in the linear chain. 68 Taking into account this limitation, we considered the possibility of developing a new strategy based on an intermolecular Nicholas reaction (Scheme 30). Because the RCM reaction has become the most powerful method for preparing cyclic products, we surmised that the cyclic ethers might be formed through a tandem intermolecular Nicholas reaction/RCM (the C-C bond-formation strategy).…”