Ruthenium-Catalyzed Asymmetric [2 + 2] Cycloadditions between Chiral Acyl Camphorsultam-Substituted Alkynes and Bicyclic Alkenes

Abstract

Ruthenium-catalyzed asymmetric [2 + 2] cycloadditions between chiral acyl camphorsultam-functionalized alkynes and bicyclic alkenes were examined, providing adducts with complete exo stereoselectivity in good overall yield and enantioselectivity (up to 99% and 166:1, respectively), as well as appreciable diastereoselectivity (up to 163:1). The diastereoselectivity showed dependence on the solvent and temperature, as well as on the substitution pattern of the reacting alkyne and bicyclic alkene components. In general, higher diastereoselectivities were observed for reactions conducted in ethereal solvents and at lower temperatures between N-propynoyl camphorsultams and bicyclic alkenes.

A DFT Study on the Mechanism and Origin of Regioselectivity in the Rhodium/Diene‐Catalyzed Ring‐Opening Reactions of C1‐Substituted Oxabenzonorbornadienes with Arylboronic Acids

“…Transition‐metal‐catalyzed reactions of oxabicyclic derivatives have been an intense area of research in the last 20 years [1a–c] . Over the years, many interesting transformations have been investigated such as cycloadditions, [2a–f] isomerizations, [3a–e] dimerizations, [4a–c] among other reactions that have been reported [5a–c] . Of particular interest are nucleophilic ring‐opening reactions of oxabicyclic alkenes, as they provide access to a broad family of synthetic building blocks bearing multiple stereocenters in a single step [6] with many of these functionalized intermediates useful in natural product synthesis and as motifs in medicinal chemistry [7a,b] .…”

Synthesis of some pyrrolidine‐2,5‐dione derivatives with biological activity against Gram‐negative bacteria

“…Several cyclobutene derivatives have been prepared via catalytic enantioselective [2+2] cycloadditions [55][56][57] using some reagents such as (trimethylsilyl)cyclobutadiene cobalt complex/lithium, [58] maleic anhydride to acetylene. [59,60] In this research, 7 and 8 were synthesized from compound 4 and either 1-Phenylprop-2-en-1-ol or eugenol using Copper(II) chloride as catalyst.…”

Versatile Catalytic Reactions of Norbornadiene Derivatives with Alkynes

“…Steric hindrance of the substituents also reduced the reactivity of the alkyne. The versatility of Ru catalysis in the [2+2] cycloaddition reaction was further demonstrated by using acyl camphorsultam‐substituted alkynes ( 74 ) and bicyclic alkenes . The cyclobutene adducts ( 75 , 76 ) were obtained in complete exo stereoselectivity in good yields and exhibited excellent levels of asymmetric induction (up to 166:1 after removal of the chiral auxiliary) [Eq.…”