A Widely Applicable and Versatile Method for the Ring‐Opening 1,3‐Carbocarbonation of Donor‐Acceptor Cyclopropanes

Abstract

A 1,3‐carbocarbonation of 2‐substituted cyclopropane 1,1‐dicarboxylates introduces various saturated or unsaturated carbon residues at the 1‐ and 3‐ position of the former three‐membered ring. Under copper catalysis, ring‐opening attack with a Grignard reagent proceeded smoothly; the intermediate was converted to the final product by reaction with appropriate carbon‐based electrophiles under basic conditions. As nucleophiles, Grignard reagents derived from sp3‐, sp2‐, and sp‐hybridized carbon residues were successfully employed, whereas various aliphatic bromides and EBX derivatives (for sp moieties) served as electrophiles.

Lewis acid-catalyzed one-pot thioalkenylation of donor–acceptor cyclopropanes using in situ generated dithiocarbamates and propiolates

“…Further optimizations by reducing the catalyst loading or use of other Lewis acids proved ineffective (entries 7-9). The use of organic bases, such as DBU and DABCO, did not yield any product, and only a 24% yield of 4a with a 4 : 1 E/Z ratio was obtained in the presence of K 2 CO 3 (entries [10][11][12].…”

“…A similar one-pot strategy for 1,3-carbocarbonation was already reported by Werz and co-workers due to the compatibility issue of nucleophiles and electrophiles. 10 Notably, organosulfur motifs hold considerable importance in pharmaceuticals, materials, and agrochemicals. 11…”

Regioselective C3–H Alkylation of Imidazopyridines with Donor–Acceptor Cyclopropanes

“…The strain energy in cyclopropane is stated to be 115 kJ/mol and this energy drives ring-opening and cycloaddition processes . The push-pull mechanism of DA-cyclopropanes, which are usually referred to as 1,3-dipolar zwitterionic synthons, makes them one of the most sought after building blocks for a number of reactions, including ring-opening events, cycloadditions, and rearrangement procedures. − …”

Intramolecular 1,2-Aroyl Migration in Spiro Donor–Acceptor Cyclopropanes: Formation of 1,4-Naphthoquinones and 1-Naphthols as Ring-Expansion Products

“…Donor–acceptor cyclopropanes (DACs) are inimitable three-carbon building blocks, whose versatile reactivity has led to the development of numerous methodologies and strategies for the access of a multitude of products . Generally, when treated with Lewis acids, DACs form transient 1,3-zwitterionic intermediates by ring-opening, which participate in annulations to give cyclic products, combine with nucleophiles or radicals to give mono- or difunctionalized products, or undergo rearrangements to give ring-expansion products . Among the various rearrangement reactions of DACs, the Cloke–Wilson rearrangements of cyclopropyl ketone to dihydrofuran, cyclopropyl imine to pyrroline, cyclopropyl ester to γ-butyrolactone, cyclopropyl amide to γ-butyrolactam, and other rearrangements such as nitrocyclopropane to isooxazoline- N -oxide involve the formation of new C–O or C–N bonds in the products (1,3-migration of carbon atom).…”