Dual Re^VCatalysis in One‐Pot Consecutive Meyer–Schuster and Diels–Alder Reactions

Abstract

A readily available oxo‐ReV catalyst has been shown to promote a one‐pot multistep process that involves the Meyer–Schuster rearrangement of alkynols followed by the Diels–Alder cycloaddition of the resulting enones. These reactions were performed under mild conditions in the presence of 5 mol‐% of the catalyst to afford the cycloadducts in good yields with almost 100 % endo stereoselectivity. In‐depth computational studies of the cycloaddition mechanism provided the preferred geometry of the rhenium complex in the transition state (TS) and corroborated the experimental endo selectivity.

Highly Stereoselective Glycosylation Reactions of Furanoside Derivatives via Rhenium (V) Catalysis

“… 3 In the same year, Fiestad delivered an alternative approach to solve the innate stereochemical problems of cyclic, five-membered oxocarbenium ions, developing an allylation reaction on a 2,7-dioxabicyclo[2.2.1]heptane ring system which uses a catalytic amount of TiCl 4 as a Lewis acid. 4 As a part of our program aimed to explore the chemistry of rhenium (V), 5 herein, we report a new talent of oxo–rhenium complex 8 , namely, its ability to promote the formation of an oxocarbenium species in a catalytic fashion ( Scheme 2 ).…”

Easy and Accessible Synthesis of Cannabinoids from CBD

“…In the current study, the preparation of Δ 9 -THC and Δ 8 -THC was approached using an oxorhenium(V) Lewis acid, (i.e., oxotrichlorobis(triphenylphosphine)rhenium(V), oxo-rhenium). 13,14 Leveraging the highly sensitive and versatile modulation of oxo-rhenium properties, the experimental conditions were finetuned by adjusting solvent, temperature, and the presence of a cocatalyst. This optimization aimed to produce either pure Δ 9 -THC or Δ 8 -THC on a milligram scale, ensuring high levels of purity for their application as analytical standards.…”

“…7 Additional experiments were conducted to assess the impact of other variables, and a detailed summary can be found in the Supporting Information. 7 For instance, the utilization of ethers such as THF as a solvent yielded inferior results, 14 and when CBD was reacted at room temperature for 46 h, 2 was obtained with a 75% isolated yield and 18% of Δ 6 -iso-CBD (9) was formed. 5 The study moved forward toward the synthesis of Δ 8 -iso-THC (4).…”

“…This novel methodology results in pure Δ 9 -THC or Δ 8 -THC through a catalytic process using a flow-chemistry approach. In the current study, the preparation of Δ 9 -THC and Δ 8 -THC was approached using an oxorhenium­(V) Lewis acid, (i.e., oxotrichlorobis­(triphenylphosphine)­rhenium­(V), oxo -rhenium). , …”

Rhenium-catalysed reactions in chemical synthesis: selected case studies

“…A one-pot Meyer-Schuster rearrangement/Diels-Alder cycloaddition was developed in 2016 in which [ReOCl 3 (OPPh 3 )(SMe 2 )] likely serves as a Lewis acid catalyst to facilitate both processes. 106…”