Reaction of cyclopropenes with a trichloromethyl radical: unprecedented ring-opening reaction of cyclopropanes with migration

Abstract

The direct addition reaction of chloroform to cyclopropenes under triethylborane-mediated radical reaction conditions to provide trichloromethylcyclopropanes has been developed. In contrast, using dimethylzinc as a radical initiator led to the formation of unconjugated esters via a domino sequence involving the addition of the trichloromethyl radical, rearrangement and ring-opening reactions.

Acylative Coupling of Amine and Indole Using Chloroform as a Carbonyl Group

“…The possible reaction mechanism for this acylative coupling is outlined in Scheme . Dimethylzinc and O 2 initiated radical decomposition of chloroform to form phosgene via the trichloromethyl radical . Phosgene is consumed immediately for the acylation of zinc amide A , which leads to the formation of the carbamoyl chloride B .…”

“…We recently reported a novel method for in‐situ generation of phosgene from chloroform in the presence of dimethylzinc and O 2 , and its application to the chlorolactamization of homoallylic amines . As part of our program studying the utility of chloroform as a C1 unit,, we report a direct three‐component coupling of amine, indole, and phosgene generated in situ from chloroform via Friedel–Crafts‐type carbamoylation [Equation (4)].…”

Synthetic Applications of Cyclopropene and Cyclopropenone: Recent Progress and Developments

“…[57] Under the influences of transition metals, cyclopropene ring experiences effective transformations under catalytic conditions. [58] Ring-opening reactions have been tempted by both thermal and photochemical activation of cyclopropene derivatives.…”

Dimethylzinc‐Mediated Chlorolact­amization of Homoallylic Amines with Chloroform

“…We recently developed a reaction for the direct addition of chloroform to cyclopropenes. This reaction proceeded through the generation of a trichloromethyl radical, which was formed by the triethylborane‐mediated cleavage of the C–H bond of chloroform [Scheme , Equation (1)] 3. We envisaged that this reaction could be applied to the synthesis of functionalized spiro heterocycles, some examples of which can be found in a variety of interesting biologically active compounds 4…”