Sc(OTf)₃‐Catalyzed Diastereoselective Formal [3+2] Cycloaddition Reactions of Alkynylcyclopropane Ketones with Electron‐Rich Aromatic Aldehydes To Yield 2,5‐trans‐Tetrahydrofurans

Abstract

Abstract:In contast to the general [4+2] cycloaddition reactions of alkynylcyclopropane ketones reported in the literature, we report herein a Sc(OTf ) 3 -catalyzed formal intermolecular [3+2] cycloaddition reaction of alkynylcyclopropane ketones with electron-rich aromatic aldehydes. 2,3,3,5-Tetrasubstituted tetrahydrofurans were obtained by this method, and the tetrahydrofuran skeleton was diastereoselectively constructed with

Gold-catalyzed intermolecular tandem cyclization/[4 + 3] cycloaddition of 2-(1-alkynyl)-cyclopropyl pyridines with nitrones: an efficient strategy for the synthesis of [1,2]oxazepino[5,4-a] indolizines

“…Dozens of methods have been reported so far. 12 The transformations of 1-(1-alkynyl)-cyclopropyl ketones (imines or oximes) have been widely studied 12 (Scheme 1a), however, less attention has been devoted to the transformation of structurally related 2-(1-alkynyl-cyclopropyl) pyridines. In continuation of our interest in strained ring involved transformations, 13 we became interested in the metal-catalyzed cycloaddition reaction of 2-(1-alkynyl-cyclopropyl)pyridines 1 with nitrones 2 .…”

Regio- and Stereospecific Hydrative Cloke–Wilson Rearrangement

“…In contrast, 1cb with strongly donating p -methoxyphenyl (PMP) gave 3cb in low yield. A two-step protocol based on Sc­(OTf) 3 catalyzed CWR and TsOH-mediated hydration provided an alternative solution for 1 with strong donors like PMP ( 1cj ) and thienyl ( 1ck and 1cl ) (Scheme ). Despite 3cg being obtained in 18% yield from highly deactivated 4-cyanophenyl 1cg , reaction of 4-CF 3 -phenyl 1ch gave 3ch in 72% yield.…”