Transition metal chemistry of cyclopropenes and cyclopropanes

Recent advances in the transition metal-catalyzed chemistry of three-membered carbocycles including cyclopropenes, methylenecyclopropanes, vinylcyclopropanes and cyclopropanes have been presented. These conformationally constrained molecules have very pronounced steric, stereoelectronic, and directing effects due to limited degrees of freedom in the system which making them versatile probes for the study of regio-, diastereo- and enantioselectivity. A diverse reactivity pattern resulting from the significant strain energy accounts for the use of small carbocycles as convenient models for study of organic and organometallic reaction mechanisms. Transition metals have revolutionized chemistry by making highly chemoselective reactions possible and expanding the scope of available transformations. It is widely used, developing and spanning highly stereoselective addition, cycloaddition, and cycloisomerization reactions, efficient cross-coupling protocols, C-H activation, and metathesis reactions.