Catalytic Enantioselective Allenoate–Alkene [2 + 2] Cycloadditions

Abstract

Catalytic enantioselective [2 + 2] cycloadditions between allenoates and alkenes is disclosed. The method functions well for a variety of alkenes, and the products are generated with excellent levels of enantioselectivity. One of the most significant aspects of the present method is that unactivated alkenes are suitable substrates for this method, which is distinctly different from nearly all other catalytic enantioselective [2 + 2] cycloaddition methods.

Cobalt-Catalyzed [2π + 2π] Cycloadditions of Alkenes: Scope, Mechanism, and Elucidation of Electronic Structure of Catalytic Intermediates

“…23−39 Enantioselective routes to cyclobutanes are even more rare, highlighted by several recent photocatalytic methods that rely on chromophores such as enones as a component of the substrate 40−45 or chiral Lewis acid catalysts. 46,47 …”

Intramolecular Chirality Transfer [2 + 2] Cycloadditions of Allenoates and Alkenes

“…3 In our efforts to extend the utility of this process, we became interested in developing variants that utilized γ -substituted allenoates. This substitution pattern renders the allene chiral and therefore presents the possibility for a chirality-transfer [2 + 2] cycloaddition.…”

“…Computational evaluation (B3LYP/6-31G(d)) 11 of the two transition-state structures reveals that they are nearly equal in energy, which is consistent with the experimentally observed low diastereoselectivity. 3,12 …”

“…Along these lines, N -activated oxazaborolidines were investigated due to their success in our prior efforts 3 and for their ability to project substituents toward the allene.…”

Synthesis, characterization, in vitro antiproliferative and cytotoxicity effects of a new class of 2-((1R,2S)-2-((E)-4-substitutedstyryl) cyclooctyl)benzo[d]thiazole derivatives

“…[36][37][38][39][40][41] Furthermore, the carbonyl carbon atoms of compounds 3a and 3b resonate at δ 213.1 and 209.1, respectively. Corner et al 42 have synthesized the ketone 3a as the single isomer and showed that the carbonyl carbon atom resonates at δ 213.3 ppm. In the 13 C-NMR spectra of the mixture, the carbonyl groups resonate at about δ 209, 206, 204-203 and 201, respectively.…”