Synthesis of 1-alkynyl-2-dialkylaminocyclopropanes and 1-alkynyl-2-diazolylcyclopropanes by reactions of 1-alkynyl-1-chlorocyclopropanes with amines and their lithium derivatives

Abstract

Reactions of 1 alkynyl 1 chlorocyclopropanes with lithium dialkylamides gave previously unknown 1 alkynyl 2 dialkylaminocyclopropanes. 1 (Alk 1 ynyl) 2 diazolylcyclopropanes were obtained by reactions of 1 alkynyl 1 chlorocyclopropanes with diazoles in the presence of KOH in DMSO at 100 °C. These reactions passed through the formation of conjugated alky nylcyclopropenes and reversible addition of amide anions to them. The regioselectivity and stereoselectivity of these transformations depend on the substituents in the starting chloro cyclopropanes and amines.

Metal-Templated Assembly of Cyclopropane-Fused Diazepanones and Diazecanones via exo-trig Nucleophilic Cyclization of Cyclopropenes with Tethered Carbamates

“…It should be pointed out that for successful base-assisted addition of the heteroatom-based entities across C=C bond of cyclopropenes, fine balance between nucleophilicity and acidity must be maintained. 4,5 Thus, the ring-retentive reaction of cyclopropenes with primary amines (9, X = NH 2 , NHAlk) cannot be achieved because the nucleophilicity of these neutral amines is much lower that of alkoxides, and their acidity is not sufficient to produce much more reactive anionic entities in the presence of typically employed weak bases. Increasing the strength of the base proved counterproductive because concurrent deprotonation of acidic C−H bonds of cyclopropene occurs, greatly diminishing its electrophilicity.…”

“…This feature allows for the utilization of strain-release driven addition of various nucleophilic entities across the C=C bond of cyclopropenes in design of bio-orthogonal transformations 1 or for the development of synthetic strategies toward novel cyclopropyl scaffolds. 2 Employment of carbon-, 3 nitrogen-, 4 oxygen-, 5 sulfur-, 6 or halogen-based 7 nucleophiles has been demonstrated in the intermolecular mode of the ring-retentive addition (Scheme 1, eq 1). The intramolecular version of this reaction involving nucleophilic species tethered to cyclopropenes and leading to the formation of fused bicyclic ring systems is much more challenging.…”